Hall's Gap, Kentucky Today

Pictured above is the "productive" side of  the Route 27 road cut in Halls Gap, Kentucky that's known as a classic locality for geodes bearing millerite needles and other sulphides perched upon vibrant pink chalcedony. With low expectations, I decided  to forgo my usual route home to Baltimore from New Orleans (Jazzfest) this May in order to pay the site a visit.

Gleaned from the Internet to form my low expectations were the  following locality descriptions:  cleaned out; filled in; hard to collect; and strictly off-limits. I assumed that most of these descriptions had been posted subsequent to the April, 2003 date where Mindat noted the locality had been reopened. After spending about 90 minutes there, I found myself unable to either confirm or deny any of these contentions.

It was easy enough to locate. Route 27 descends a hill with road cuts on either side immediately north of the Halls Gap Motel.   Where  the road cut ends on the right is a pull-off where you can park. Everything that I collected came from within or the immediate vicinity of that parking area. Hereabouts was enough "geode material," to distract me for a half hour before venturing back to the road cut. Unless one counts the presence of snakes---I observed but one---there were no signs or obstructions to discourage me from collecting.

The cut is through shale. Nowhere in the road cut or amidst the talus beneath it did I observe any other kind of rock. Having since learned that the sulphide-bearing geodes were wedged into the shale in the road cut,  it's possible I didn't look carefully enough. However, if the geodes were there, the work to dislodge them would have entailed more time than my schedule permitted.

So it was back to the parking lot to further inspect what was on the surface there and immediately beneath. Included were numerous geode particles, a few clusters of  quartz crystals to about 5 mm. and quite a bit of  nodular chalcedony, some of it drusy. Exposure to the weather had had dulled any prior vibrancy the chalcedony might have once enjoyed.  I also uncovered a few unbroken geodes ranging in diameter from approximately one to five inches. They were plenty tough to crack. Inside them were chalcedony that curiously appeared as weathered as that which  had lain exposed on the ground,  and plenty  of cleaved calcite along with a few rhombs. Some examples are shown at right.

Once again after the fact, word has reached me of other geode localities in the vicinity of Halls Gap. It has not include word regarding a presence of millerite or other sulphides.
.

Baltimore City Diggings at Herring Run

Nearly every day for eight years during a much longer than eight year hiatus from mineralogical pursuits, I walked  the paved loop on either side of Herring Run between Harford Road and Belair Road. Even though these walks were for no purpose other than exercise and the enjoyment of being outside, had there been much of mineralogical interest along the way, I probably would have noticed.  Except for the alluvial deposits in the stream, this stretch of Herring Run Park was all mica schist that was so boring I don't recall  ever noticing any other rocks or minerals associated with it.

 Having moved on to other means and places for daily exercise and outdoor activity, ten years passed without my even once visiting the park again. Prompting me to return recently were digging and blasting to replace aging and decrepit sewer pipes that run adjacent to the stream.  To reach the above pictured spoils from it by car, take the spur extending southwest from Harford Road immediately south of its intersection with Argonne Drive. Park where the spur ends, walk under the bridge along the north bank of Herring Run, and you'll be there.

As expected, most of the rock here is the same boring  mica schist. Associated with it, however, are  intrusions of  feldspar and massive smoky quartz. Most interesting of the latter two is the feldspar, some of which is  attractive enough to be collected in its own right, as shown at left.

Most of the  feldspar, however, is lighter in colour and  more coarse. Often it occurs in combination with the mica schist and the smoky quartz.  These rocks are often the most interesting  to break open and explore.

The schorl crystal shown at right measures 3 cm. x 1.8 cm. and was one of the smallest, albeit easiest to dislodge schorl crystals in the larger rock from which I trimmed it. That's the good news. The not so good news is that very few rocks  I observed bore any schorl.

Garnet, which I assume to be almandine, is more likely to be inside  this rough feldspar material. The chances of finding or  extracting an unbroken crystal of significant size could be slim. However,  the  colour and luster of these garnets are notably gemmy.

I'd be surprised, to find any other mineral species at this locality. None of the material here is vuggy, and examination of it under the scope has revealed nothing of interest. Still, it's a spot in Baltimore City, that for now, at least when the workers are not present---think early evening and weekends--- should probably be all right and perfectly safe for collectors to crawl around in the dirt  and hammer away. And undoubtedly, further blasting in the future will take place downstream to provide additional  material to check out.

Real Cerussite Magic

After 118 posts dating from  February, 2009, this is the first mention that in addition to collecting minerals, writing about them, and photographing them, I'm also a dealer with a store (Jakes Minerals) on eBay, under the handle "Bestyards." Selling minerals on the Internet is great way to  learn about as well as appreciate species, localities, mineralogy in general. It results from time spent through  research---I do a lot of it on Mindat---to ascertain that inventory descriptions are accurate, especially regarding species and locality.

So it was with the cerussite specimen pictured in our title picture next to its label. Was cerussite REALLY that rare at the Moose Mine? And for that matter, was the specimen actually collected at the Moose Mine in Butte, Montana?  After considerable research, uncertainty lingered. Mindat, for instance, listed but six species occurring at the Moose Mine, none of them lead bearing (as is cerussite). Nor did Mindat note a presence of cerussite at hardly any of dozens of localities in the  Butte vicinity. Out of 2,548 images of cerussite on the Mindat site,  not one was from anywhere near Butte.

So below is a copy of the listing I posted on Thursday, April 20, 2012:

The listing had not been posted for less than two days when the following note showed up in my eBay mailbox:

Dear bestyards,

He (Pequa Rare Minerals) was trying to give the dates that the Moose Mine was operating, not the date the specimen was recovered. It did come from 1880 workings, but I collected that specimen about 20 years ago along with a flat of specimens. The biggest piece I donated to the Montana Tech Mineral Museum. I traded the one you have to J. P. (4th best found) in return for a small Butte bornite xtl specimen. As to the locality, it is from the outcrop of a vein near the Moose shaft. As I was collecting the material, the ground under my feet began to shake, then a finger-sized hole appeared and dirt began to drop into it. I realized I was on top of a thin ledge of rock (called a crown pillar) that had been mined to within a few feet of the surface. I realized if I tried to dig any more the ground would collapse, and I would fall to my death into a large open stope. So yes, this is a real Butte cerussite. The small flat of specimens collected are the only ones known. 

The mining engineer who collected this unusual and obscure speciemen  20 years ago  had inadvertently  encountered its image amidst the millions on the Internet.  Though disdainful  of  the metaphysical claims sometimes accredited to various minerals, I'm hardly averse to the notion that working with minerals ushers more than its share of seemingly magical synchronicity. Here was just one example.

Needless to say I removed this Moose Mine cerussite specimen from the market immediately. It currently rests at a cherished spot in my main collection cabinet. Who was it, after all, who proclaimed that  if the label were correct, the specimen  "could be a treasure?"

New Treasures at Delaware Mineralogical Museum

The master German stone carver Gerd Dreher fashioned the bat entirely from a single chunk of Brazilian agate. It's on loan from the private collection of Herbert and Monika Obodda. And the frog, at left? Except for the eyes and flower's ovary, it's but one piece of the classic Tanzanian ruby zoisite combination. These and other Dreher carvings will be on display until July 20, 2012.

They are but a small part of what is new here at the Delaware Mineralogical Museum in Penny Hall at the University of Delaware. Otherwise, it's all world class mineral specimens that intricate fiber optic lighting showcase with a flair not likely surpassed at any other mineral museum on earth.

Why is it that of the United States of America's 50 states, one that ranks at or near the bottom of the mineralogical wealth ladder boasts such a collection? Several reasons: Generous donors have funded it; it's small enough to focus on the best of the best; and it has Sharon Fitzgerald as its full time curator.

Aware of my interest in regional minerals,
Sharon had mentioned to me in an email one new item in particular that was not on display. She described it as a "book by W. W. Jefferis---really just a cover that between dividers contains sheets of muscovite that are all included with magnetite and hematite from Chandlers Hollow." Even with the picture at left, I was not entirely certain what to expect. After all, mica crystals in nature form as "books." Jefferis collected the numerous muscovite crystal sheets between as many dividers about a century and a half ago. Though Chandlers Hollow still exists, Ms. Fitzgerald has not been able to determine specifically where at Chandlers Hollow they came from or how Jefferis collected them.

Still, the Delaware Mineralogical Museum is less about art and history, more about world class minerals. Ms. Fitzgerald insists that despite the colour of its backdrop, the aquamarine pictured at left is truly as blue as it appears to be. In fact, some of the specimens on display here could be the most visually outstanding examples of their species known to exist. Aware of the extent that such determinations, especially with respect to common or frequently collected minerals, are subject to argument amongst curators, collectors, and high end mineral dealers, I picked a less commonly displayed species to illustrate this point. Is anyone aware of a more outstanding kurnakovite specimen than the foot long piece from Boron, California pictured at right?

Though the Dreher carvings will only be here until July 20, the amazing mineral specimens will be around indefinitely. However, anyone planning to visit this April (2012) or June should first call 302-831-6557 or 302-831-8037. Scheduled renovations elsewhere in Penny Hall will necessitate closing the museum for a period of time during one of those months. Otherwise, except for holidays and school breaks, it's open Wednesday, Friday, Saturday, and Sunday, noon to 5, and on Thursdays from noon to 8.

Mineralogical Ramblings in Cecil County, Maryland

Threats of an earlier than usual presence of briars, ticks, and snakes this spring of 2012 prompted me to spend an inordinate amount of time the past couple of weeks searching for minerals in rocky and wooded areas. Much of the focus has been in Cecil County, Maryland, on either side of of Pilot Town Road and Pleasant Grove Road as they approach the the Mason-Dixon Line.

Though most of the land hereabouts is stringently posted, it is dotted with abandoned quarries, prospects, and pits once variously worked for talc, feldspar, chromite, and serpentine. Most mineralogically significant of these were the State Line Pits, of which the dumps are now buried beneath earth overgrown with briars. Though this locality produced Maryland's finest williamsite in years past, it's long been inaccessible. The most recent attempt to collect at the State Line Pits of which I'm aware was by an accomplished collector who gained access to the site 18 years ago and after digging extensively, returned home skunked.

After having gained permission to visit the sites of other long abandoned and grown over workings in this part of Cecil County, I've concluded that the best place in to look for the greatest variety of interesting minerals is in the area's more accessible alluvial deposits. In the Pilot Town Road vicinity, my recommendation would be Conowingo Creek immediately north of the bridge where the Pilot Town Road bridge crosses it.

The most collectible species here are chalcedony and jasper. To spot them, look for rocks with dark, rough, and mangled surfaces, then break them open if necessary to be certain. Any green rocks, of course, are serpentine. Much of the serpentine that was mined in this immediate vicinity and thus most likely to turn up in alluvial deposits is of the verde antique genre, which is wonderful as a building stone, but should bore most collectors. More collectible and interesting serpentine is readily available in the ubiquitous roadfill hereabouts that's quarried from Lancaster County's Cedar Hill Quarry or Penn-Maryland Quarry

To find a piece of serpentine, variety williamsite,
however, would be another matter. Alluvial deposits along Octoraro Creek or its tributaries should offer better odds as they flow closer to williamsite localities, mostly in Pennsylvania, that have produced the greatest quantities of this dear and cherished species. I've not yet explored the Octoraro deposits, but was standing by recently when a collector pulled the amazing piece at right from an Octoraro tributary just a short distance north of the Pennsvlania line.

Pebbles of reddish quartz or quartzite, especially with vugs or holes that could once have encased crystals, are worth a whack with the hammer. The red colour is from iron, which could signal a presence within of sulphides, namely pyrite, chalcopyrite, goethite pseudomorph after pyrite, or magnetite. Particularly interesting was the specimen at left. It is from inside a larger and less water polished, but otherwise similar rock in nearby field we visited after leaving the alluvial area. Note how it bears goethite pseudomorphs after pyrite crystals immediately next to pyrite that had not so much as tarnished.

Also curious was the shiny white material that appeared when I broke open the Conowingo Creek alluvial quartz pebble pictured at right. For all the world, it looks to me like brucite. Though indigenous to the region, brucite is not a species I would expect to uncover when breaking open a piece of quartz. Even after examination under the scope, I don't have a clue.

Finding corundum amidst these thousands of rocks would seem more likely. Having recently searched for it to no avail in alluvial material along the Patapsco River near Henryton in Carroll County, MD, corundum was on my mind. That, of course, is where Bob Conkright made the corundum find of his life. There as in this part of Cecil County, the abundant presence of talc, feldspar, quartz, and serpentine in close proximity create the right environment. Considering reports of corundum nearby along the Nottingham Turnpike just 1 1/2miles northeast of Chrome, PA, and with hundreds of tons of corundum having been mined during the 19th Century at various geologically similar locations in neighboring Chester County, PA, why not?

The Wood's Chrome Pit Today

First of all, to properly learn about this classic Lancaster County, Pennsylvania locality near the Township of Little Britain and very close to the Maryland Line, one should read Wendell Wilson's article in Mineralogical Record, July-August, 2011, Volume 42, Number 4. It even has maps showing the location.

Conveniently for the very nice property owners, this edition of the periodical came out at a time of year when enough copperheads and poison ivy were around to discourage any onslaught of collectors.

Notwithstanding MinRec's maps, or even if using GPS, the locality is not easy to find or reach. Only through the kindness of a collector who had previously visited the Woods Mine and understood the necessary protocol for gaining access and permission to collect did I manage to get in. The collecting takes place on dumps surrounding a water-filled pit.

These dumps are numerous and all worth checking out. A picture in MinRec shows one area where in 2010 a backhoe had overturned new material. Notwithstanding, I enjoyed my best luck on dumps that appeared to have withstood the ages.

MinRec's images of Wood's Mine specimens practically render its author guilty of understatement for noting that "none of (the more recently collected material) rivals the specimens found prior to 1881." That was also the year the mine closed. On the other hand, numerous minerals worthy of collecting remain. Still abundant and occasionally of quality sufficient for display is the reddish eggplant coloured chrome antigorite, (var. picrolite), such as pictured at left. The same can be said for rich massive chromite, as shown at right. With a bit of luck, I suspect that one might still find a piece of chromite coated with traces of the deep emerald green nickel carbonate zaratite. It interested me, however, to note recently on MinDat, that the IMA status of this much cherished by collectors species was "questionable."

Even more questionable is the bright and colourful nickel-bearing material known as garnierite, which MinDat refers to as "the result of lateritic weathering of ultramafic rocks (serpentinite, dunite, peridotite)--- mostly a mixture of various nickel and nickel-bearing magnesium layer silicates." I've also encountered it labeled as deweylite when in association with white magnesite as shown at left. My hunch, however, is that one with better knowledge of the Wood's Mine and its species would simply refer to it as antigorite.

I'm not aware of a species that assumes more forms, colours, varieties, and names than antigorite. One that's unmistakable as well as the creme de la creme of the antigorites, is williamsite. Prized by jewelers and carvers, its transluscence and a presence of chromite specks within are what distinguishes it. Albeit a scrap, I consider myself fotunate to have uncovered the thumbnail sized piece at right.

Of all the different species for which the Wood's Mine is known, the world- class brucite specimens collected there in the mid-1800's brucite are the most famous. Brucite sufficient for reference can still be found on the dumps, though it is not abundant. The best I could come up with is the very weak example (shiny material) in the image at left. Another once abundant species that I feel certain is also still around is kammererite, penninite, rhodochrome, chromian clinochlore, or whatever other name one has for it. I found but specimen that arguably bore traces of such material. The other side would proclaim the little piece I found to be chrome antigorite. Especially in very small quantities, it's easy to confuse the two. Kammererite is distinctly micaceous.

The Wood's Chrome Mine is but one of numerous localities amidst serpentine barres that cling the Maryland-Pennsylvania Line. All that are accessible should prove worthy of a visit.

Uncommon Finds in Harford County, Maryland

Recently, an email came in from a Mineral Bliss
reader named Deb who lives near the northwestern corner of Harford County, Maryland. She said she had found microscopic flakes of gold in a nearby creek. She also reported having collected a large ilmenite specimen amidst rocks directly across the road from her house. Rutile, she said, is "everywhere out here." Deb was born in this area. She has lived hereabouts most of her life and collected minerals since childhood. Needless to say, I was intrigued and promptly made arrangements to visit.

Shortly after my arrival, Deb suggested we go for a drive. Heading east on Maryland Route 136 , we drove through an area where quartz had frequently intruded amidst late Precambrian Upper Pelitic (Wissahickon?) schists. The quartz hosts all the ilmenite of which Deb had spoken and once hosted the rutile crystals, most of which have separated and typically occur loose in alluvial deposits and plowed fields. Regarding the latter: "Some fields have a lot of rutile,"Deb explained, and some don't have any." She drove me by a cornfield very close to the Pennsylvania Line where the owner had given her permission to collect. Though mostly covered with remnants from last summer's crop, enough stones were visible for us to pluck a few rutile crystals and two pieces of ilmenite with quartz.

The geology in this part of Harford County is fascinating. Farther east on Route 136 near Whiteford, Deb pointed out woodlands to the north that host a large opening that was once the Williams Slate quarry. Circling the immediate area of this opening , a geologic map of Harford County shows a ring of rock referred to as the Volcanic Complex of Cecil County. I surmise that the site of the old Cardiff Serpentine Quarry, once noted for its Verde Antique building stone, sits somewhere within the boundaries of that ring about a mile farther north at the Pennsylvania line.

We continued driving east on Route 136, passing the crossroads of Dublin, from which a short road leads to sites where talc was once quarried in large steatite openings. Uncertain regarding accessibility, we continued southeast on Route 136 for another mile to Route 1. There we turned left, and headed northeast across the the bridge over Conowingo Dam into Cecil County. Near Conowingo, Deb quickly led me to a spot where we found a small piece of rhyolite from that county's aforementioned and eponymous Volcanic Complex. Though the country rock here was Port Deposit gneiss, the origination of rhyolite pieces sparsely scattered on the ground been traced to a location within Cecil County's scattered Volcanic Complex somewhere between here and Northeast, Maryland. It was my first encounter with Maryland rhyolite.

From here we headed back to Deb's house where she had yet more that was interesting to show me. In a vial with those sparse flakes of gold she had panned from the stream near her house was a silver coloured nugget, measuring a fraction of a millimeter, that looked like platinum, which would certainly be very unlikely. Having since taken time to study its photomicrographic image, however, it screams micrometeorite! We're eager for word from any readers with different ideas.

In a lifetime of collecting, Deb has come up with a lot of interesting material from other parts of Harford County. Though hardly known for its pegmatites, Deb was at hand about 20 years ago when the construction of a driveway uncovered a small pegmatite outcrop within a mile of where Route 1 crosses Deer Creek. It was here that she collected the beryl crystal pictured at left, the only example of the species that I've seen from Harford County. The same locality also yielded the specimen at right, which appears to be two columbite crystals in feldspar. Assuming a correct visual identification, this is not only the sole columbite I've encountered from Harford County, but from anywhere in Maryland. Deb also collected the chalcedony pictured at left from a spot close by where the local rock was metagabbro.

Finally, and again at least several decades ago, Deb uncovered an amethyst crystal on a long since built over farm on the south side of Route 1 very close to where it crosses from Harford into Baltimore County. Although the Natural History Society of Maryland's 1940 Minerals of Maryland publication by Ostrander and Price reports amethystine drusy quartz from Mine Fields, this is the only find of an actual amethyst crystal that that I'm aware of from Harford County. Since her crystal was marred with its share of dings, Deb had cut from it the pendant pictured at left next to the remains of the original crystal.

Interestingly, all of the species Deb has found that seem so unusual for Harford County are present not far across the Mason-Dixon Line in Southern Pennsylvania, where the Piedmont geology is relatively similar. It should also be safe to say that Pennsylvania, over the years, has attracted a lot more collectors to uncover them.

Tucson: 2012 and Every Year

Each year from the final Friday in January through the second week of February, the city of Tucson, Arizona hosts the world's premier extravaganza featuring minerals, gems, beads, lapidary supplies, fossils, and meteorites. It all takes place in motels and tents all over town and culminates with "The Big Show," which happens at the Tucson Convention Center from the second Thursday of February continuing through Sunday. Regarding minerals, each year's show has a theme. The 2012 theme was "Minerals of Arizona." Otherwise, it's much the same from year to year. The usual vendors set up at their usual spots, while the times and locations of the lectures, banquets and symposia change little.

Mineral people come to look, sell, learn, network, schmooze, and most of all to purchase. Buyers who arrive when the action begins in January are likely to have first shot at new finds and other much in demand material. Prices of specimens can range from a couple dollars to well into six, even sometimes seven figures. Differences in price of pieces that would appear to be of similar value can also cover a vast range. The prices of some specimens can increase over the course of the two week period as they change hands from one dealer to the next. Prices can also head lower as well, especially at the end of the show when some dealers would rather accept less cash than haul home certain rocks. The word "keystone" is heard frequently. It means half price. "Double keystone" is where a price already cut in half is halved once again.

Prior to the Big Show, the nexus of the mineral action is at the enormously spread out Hotel Tucson City Center (formerly Inn Suites) at 475 North Granada. Another much smaller venue not far away but worth checking out is the Mineral and Fossil Marketplace at Oracle and Drachman featuring some respected mid-range dealers who operate from tents. Also close by at Speedway and Main are yet more tents manned primarily by Moroccans. Along with fossils, they have flats and flats of such signature material from their country as malachite, azurite, erythrite, cobaltian calcite, cerussite, barite, skutterdite, quartz geodes, epidote, pyrolusite, goethite, and occasional yellow apatite---though not too much else. Across town, the Quality Inn on Benson Highway is loaded with mineral dealers, mostly from China, India, Pakistan, Afghanistan, and Russia. Additional activity extends for at least a mile in motels along the service road paralleling I-10 as it passes downtown Tucson. Though mostly gem and fossil oriented, some great deals on minerals are occasionally available from a relatively few mineral dealers who typically specialize in but one or two species. The same is true at other venues, such as the Kino Complex and Tucson Electric Park.

The only truly unique event during the period leading up to the Big Show happens the previous weekend at the Westward Look Resort. On Saturday, a great private collection graces the main lobby. On Sunday night, following a social hour, there's a presentation by someone accomplished and well-known in the mineralogical arena. Featured this year on Saturday was the collection of Ron Gladnick. On Sunday evening, the legendary 94 year old Ed Swoboda presented an overview of a long life devoted to gems and minerals. Most definitive of the Westward Look Show, however, is what goes on in a couple dozen adjoining private suites where just about every well-known high-end mineral dealer on the planet has set up shop. The quality and beauty of the magnificently displayed minerals for sale are no less mind-boggling than the numbers on their price tags.

With the Big Show underway on Thursday, the Convention Center becomes the focal point, although business continues at other venues around town. Mineral specimens from various collections, both public and private, are displayed in cases, mostly in the northwest portion of the main hall. Dealers of minerals are located near these displays as well as throughout the western part of the main hall. Though differences in price for similar specimens continue to be wide as ever, the popular perception is that everything costs more at the Convention Center. Notwithstanding, plenty of bargains are around for those with the wherewithal to seek them out.
The Big Show is also the site for lectures, programs and seminars. World famous gem and mineral photographer Jeff Scovil, who withholds no secrets regarding his techniques, gives a two hour instructional presentation each year on Thursday. This year he concentrated on creating backgrounds for photographing minerals.

The Arthur Roe Micromount Symposium takes place all day Friday upstairs in the Turquoise Ballroom. In addition to the speakers (I caught a great illustrated talk by Bob Meyer on the microminerals of Tiger, Arizona), are numerous "giveaway tables" with flats and egg cartons of material sorted according to locality. It's there for the taking, and most of it begs for scrutiny beneath the scope for brilliant, rare, and beautiful treasures.

In the adjoining Crystal Ballroom, a succession of speakers holds forth all day, most of them covering topics related the given year's theme, this year minerals of Arizona. The scene here is much the same on Saturday as Friends of Mineralogy, the Tucson Gem and Mineral Society, and the Mineralogical Society of America host an annual symposium that once again features renowned speakers, most covering topics related to the show's theme.

Although the Big Show continues through Sunday, what for many attendees is its climax happens Saturday night over cocktails, an auction, dinner, and ultimately the presentation of numerous mineralogical awards. The grandest of these is the prestigious Carnegie Mineralogical Award. This year's recipient was Dr. Jeffrey Post, Curator-in-Charge of the mineral collection at the Smithsonian. Also notable is the level of ceremony recognizing the mineralogical accomplishments of young people. This has much to do with the longing of older mineral folks to see their hobby perpetuated. They sense that in this modern age of technology, diminishing numbers of youngsters are getting involved.

Next year's Big Show theme will relate to the many forms, habits, and localities for the common but often spectacular mineral fluorite. Otherwise, we can feel assured that all will be much the same as it was this year and preceding years. For sure Tucson will continue to provide a world class opportunity to enjoy, view, and learn about minerals. A few that I observed with particular awe can be seen at this link.

Opal at Bare Hills

Most likely opal is not uncommon as a coating on the serpentinite rock at Bare Hills along either side of Falls Road about a mile north of the Baltimore City line. Yet, I doubt that opal is on the radar of those prone to collecting here. At least, I've never heard anyone mention it, nor had I ever seen any Bare Hills opal. My only awareness of opal at Bare Hills was that Ostrander and Price's long out of print Minerals of Maryland (1940, Natural History Society of Maryland) named it as one of the species occurring at the two adjacent and long abandoned Bare Hills Serpentine Quarries as well as the surrounding barrens once dotted with chrome pits.

For the sake of reference, the image at left shows the westernmost and better recognized of those two former serpentine quarries along Falls Road. It was a good collecting spot until fenced off and declared off-limits by its owner, the Gerstung Inter-sports facility located at the end of Coppermine Terrace*. More accessible on the other (east) side of Falls Road, its presence mostly obscured by vegetation, is the second abandoned Bare Hills Serpentine Quarry. The ultramafic rocks comprising its talus, while not as interesting as the rocks I remember from years ago at the western opening, yielded my opal (var.) hyalite.

A dull blue-grey glint on a rock encrusted with tiny whitish globular dots caught my eye. Observing through the loupe, I assumed the dots to be magnesite or hydromagnesite, which ubiquitously forms massive coatings on similar rocks throughout the Bare Hills area. The globular presence was distinct enough that it prompted me to bring the piece home for a look under the scope. The right side of this post's title image shows the surface of this rock at 40x. No question that the coating is opal, whose obscurely reported presence at Bare Hills had mystified and fascinated me for more than 50 years.

Since the appearance of this rock was so similar to hundreds of rocks hereabouts, I suspect that opal may not be that elusive at Bare Hills. This certainly was not the first time I'd seen rocks in the area that were visually similar, at least at first glance. Otherwise, except for occasional birdseye chromite in weathered serpentine rocks along with a few veins of chrysotile, there seemed less that was likely to interest collectors than I recall from years ago at the quarry on the other side of Falls Road and the chrome pit dotted serpentine barrens surrounding it.

Though off-limits where not built over, my hunch is that those barrens on the west side of Falls Road, unlike those on the east side of Falls Road that surround the site of my recent visit, always were and still could be more interesting. They will be the topic of a Mineral Bliss post at some point in the future.

*It could be that the name of "Coppermine Terrace" was conceived in ignorance. In its entirety, Coppermine Terrace passes exclusively through serpentine barrens formerly worked for chromium only. The site of the former Bare Hills Copper Mine is approximately two miles away and set in a completely different landscape.

Bob Conkwright Reflects on his Giant Maryland Corundum

Our recent Jan. 6 topic, "An Humongous Maryland Corundum," gleaned more hits than any previous Mineral Bliss post has ever received. How did this specimen get to where Bob Conkwright, Jr. found it back in 1960 amidst the dumps of one of the Devries Quarries, which even then were long defunct? Regardless of whether the piece was actually quarried there, which is open to question, we can be quite certain at least that it formed close by, somewhere near this Henryton Tunnel less than a mile north of Marriottsville.

When we spoke late last December in Bob's office at the Maryland Geological Survey, he referred to this find as "my heritage," and needless to say it had much to do with how and why he went on to make geology his career. Surely Bob has given plenty of consideration to where this amazing specimen came from and how. Here are his thoughts:

There are many references available on corundum digenesis. Looking at page 90, “Geochemical Methods of Prospecting for Non-metallic Minerals”, (Komov, I.L., 1994)*, the author indicates six recognized primary corundum deposits. Corundum is commonly associated with mafic and ultra-mafic rocks (silica-poor), pegmatites (which are typically not silica-poor), and marble (which can be relatively silica-poor). If you look through the various scenarios for corundum formation, a couple of items stand out. Bedrock in the Patapsco Valley has pegmatite and marble, and in places, pegmatites intruding marble. According to the 1928 Carroll County geologic map, the easternmost Henryton pegmatite dike is in contact with Cockeysville marble. The pegmatite/marble associations in the valley are known to include albite, diopside, phlogopite and pyrite, all minerals listed as associated with corundum. Given the size of the crystals, the corundum mass is almost certainly pegmatitic in origin, and the Cockeysville marble could have supplied the necessary silica-poor environment for the reaction to occur. Given the large size of albite and diopside crystals known to exist in these formations, I think it is not unlikely the pegmatites that injected into the marble are a likely source.

I have not found any mapped occurrences in this part of the State where pegmatites intrude silica-poor ultramafics or serpentinites. This has occurred around the Pennsylvania border, and corundum is known to occur in those formations. Red corundum crystals were reported in pegmatite-associated serpentine, which also produced talc, actinolite, chlorite and other silica-poor minerals **. There are soapstone quarries in the Patapsco area, so perhaps there are pegmatite-injected serpentinites that have not yet been identified.

Since the large crystal size would indicate a pegmatite source, but no known pegmatite dikes are injected into these local, silica-poor rocks, I suggest the specimen came from the local marble. This leaves the mystery of the reddish color, known to be derived from trace chromium. I have an idea, which might be a bit lame, but it is the only one I have for now. According to the 1993 Geologic Map of Howard County, John Edwards interprets the Patapsco Valley pegmatites as Silurian in age. The mafic and ultramafic complexes in the region are interpreted by Edwards as older than the pegmatitic injection. Could it be that the injected magma picked up some chromium ions during the intrusive event into the older marbles? Perhaps.

I am certain the corundum mass was loose in dump material, or possibly just in the soil/saprolite layer. Given the hardness of corundum and the rapidity with which calcite and feldspar weather, it is not unreasonable to assume the crystals, if not derived from quarried material, weathered out of the bedrock. There are some parts of the crystal mass which look to me like they have been weathered and polished, which would take a long time to do to corundum. This makes me think the specimen is eroded rather than quarried. With that in mind, maybe there are more!

The more I think about it the more intrigued I am with the possibility that some of the Howard county soapstone bodies may be serpentinite hydrothermally altered by pegmatite injection, similar to those in the MD/PA line area. Although pegmatites have not been mapped near most of these bodies, it is entirely possible they were not observed. For instance, the Henryton pegmatites are clearly seen on the 1928 Carroll County geologic map, but are absent on the 1993 Howard County map, right across the river. Did those dikes really do a dead-stop at the river’s edge? I don’t think so.

Contributed by Bob Conkwright

An Humongous Maryland-Collected Ruby Corundum

Weighing 16 pounds, and measuring 8 1/2 inches x 6 inches x 5 inches and pictured above is the most spectacular and amazing Maryland collected mineral specimen of thousands upon which I have gazed. Shortly after a 2009 visit to the Maryland Geological Survey's Baltimore headquarters on St. Paul St. to view its Maryland minerals on display, my friend Jeff Nagy inquired if I'd seen a gigantic Maryland corundum rumored to be there. Absolutely not: To the best of my knowledge, no Maryland-collected corundum specimens were known to exist.

Two and a half years later, Jeff called and invited me to accompany him to the MGS building for a visit with geologist Bob Conkwright, Jr., MGS Program Chief for Coastal and Environmental Geosciences. It turned out that for many years, this amazing specimen had served as a cherished doorstop in Bob's office.

Bob collected it circa 1960 at age eleven in the company of his father while collecting at one of the three long abandoned Devries Quarries in Carroll County. Once mined for feldspar, two of the Devries openings sit adjacent to each other along a bluff overlooking the Patapsco River near Hentryton. Bob explained:

"Start at the Henryton Tunnel and head downstream. The area was not as wooded back then, and there were just piles of dumps. I saw the weathered end of this thing sticking up and kicked it, hurting my toe. After a little digging, I first suspected it was some kind of hexagonal quartz cross-section."

About a week after our visit with Bob, my friend Harold Levey joined me on a short hike heading north up the railroad tracks along the Patapsco from Marriottsville looking across the river for a spot that could be where Bob made his find. Sure enough, about a hundred yards downstream from the Henryton Tunnel, the two openings remained. Although a few pegmatite rocks were visible on the ground, any dumps that may once have existed had long succumbed to fluvial forces and/or been buried with soil as the area has become heavily wooded. Even so, a few pegmatite rocks were visible. Now part of Patapsco State Park, prohibitions against collecting are actively enforced with inordinately costly penalties.

Open to question is whether this amazing piece was actually quarried from one of the openings upon whose quite shallow dumps Bob collected it. Could it have been loose in the soil/ saprolite layer, or even a product of blasting for construction of the Henryton Tunnel near the turn of the 20th Century? Bob Conkwright is eminently qualified to tackle these questions and has agreed to commit his thoughts to writing for an upcoming sequel to this post.

What is clear, however, is that this unique find from a half century ago makes a strong case that additional corundum is somewhere about. And fortunately, there's no law against checking out the various ever-changing alluvial deposits in and along the Patapsco as it heads downstream.

John S. White Compares Munich to Tucson

A May-June, 2009 article about John S. White by publisher Thomas P. Moore of Mineralogical Record (which John founded in 1970), mentioned how "some less than reverent visitors used to ask permission to dig in the hypothetical pile of discarded matrixes in John's back yard." Though more reverent than that, I had little compunction about eyeing the pebbles in his driveway as we walked out from his home in Stewartstown, PA for lunch at a restaurant in nearby Shrewsbury. The calcite and epidote in our title picture were the bounty.

John had recently returned from the annual late autumn Mineralientage München (Munich) show. Though my visit was primarily social, I was interested in learning as much as possible from John about how this event differed from the extravaganza that transpires from the end of January through the second week of February each year in Tucson.

Most significant, John noted, is that Munich has no fringe shows and no hotel selling. The event is open to the public for two days only and takes place at a single location, namely the four huge halls of Neuen Messe München. Each of these four halls is larger than the Tucson Convention Center.

Partial compensation for the lack of fringe shows and hotel selling is a policy at Munich that allows admission to certain high-end dealers and well-connected advanced collectors during set-up period, which begins on Wednesday and continues through the following day. Doors open for collectors on Friday. The general public gains admission only on Saturday and Sunday.

Mineralientage München consists of four "worlds:" Mineralworld, Gemworld, Fossilworld, and Stoneworld. While the titles tell the story, it's notable that Gemworld has a few gem minerals and that the wares in Stoneworld not only run a new-age gamut, but can include everything from interior acoutrements to hot stone massages.

My conversation with John focused mostly on Mineralworld. Along with world class exhibits---2011's Show featured European Classics---Mineralworld is divided into sections, halls unto themselves. The "super-premium dealers," as John descried them, operate from the most elaborate stalls in a walled in section. With dealers of all stripes in between, Mineralworld also accommodates dealers small enough to be clustered where each could have as little as a meter of space.

Scattered throughout are Chinese, Afghan, Pakistani, and Indian dealers. The quality and prices of their merchandise can vary from one hall to another. The Chinese dealers, says John, are likely to have the best material and the most new finds. Regardless of nationality, John emphasizes that as in Tucson, quality and prices are all over the map and often far from commensurate.

Moroccan dealers by the dozens are clustered in another hall and as at Tucson generally have more predictable inventory that varies little from year to year. The question was(is) how can they all make enough money to keep returning? The answer, John says is that they are there for many reasons, not just to profit on their mineral sales.

Notably different from the “Big Show” in Tucson, John states with emphasis, is that "excellent food courts are all over the place," with much better fare than available at the Tucson Convention Center. The catalog for the Munich Show is also a lot slicker than at Tucson. John gives me one shortly before I leave.

Walking once again the few steps across the driveway from his door to my car, I stoop to pilfer another pebble, because unlike the others, it's quartz. About to toss it later as the waning natural light in my office rendered little of interest to be visible, I opted first for a quick glance under the scope. Revealed was the phlogopite micromineral at left.

Collecting at the LeFarge Quarry in Churchville, MD

The LaFarge Quarry in Churchville, Maryland, has become a popular field trip destination in recent years for mineral societies that have the proper insurance and whose members adhere to carefully stipulated safety regulations.

The collecting takes place along the berms on either side of two benches. Most of the rock is gneiss or metagabbro that can be boring to observe. But for the collector who knows where and how to look, it offers up a significant variety of minerals.

The quarry walls show occasional zeolite intrusions clearly visible from the benches below. On a recent trip sponsored by the Baltimore Mineral Society, several members uncovered and extracted some fine specimens of stilbite and chabazite from the berm beneath such an intrusion. They did so by attacking promising looking large boulders on the berms with sledge hammers and by turning over the smaller boulders and rocks amongst them. A significant find by any measure was the specimen displaying balls of stilbite crystals in the box at right,

Just as remarkable was a foot long vuggy vein of exquisite pseudorhombic pink chabazite crystals in another boulder beneath this same intrusion. Trimmed of a few hand specimens, the particularly impressive crystals remaining in the boulder appeared unlikely to survive further trimming on site without serious risk of damage. The circumstances prompted the seasoned and skilled collector who'd first spotted it to haul home all 25 pounds of the partially trimmed boulder that remained. Associated with the chabazite were a few small heulandite crystals.

Plucked as you see it at right from a point along the berm at least fifty yards beyond the zeolite veins in the quarry wall was the laumontite piece shown at right. Though a keeper, it falls far short of the best this locality has been known to produce.

Vugs in the rocks and boulders along the berms are scarce, and whenever noticed are worthy of checking out. One such vug yielded a pair of colourless and nearly transparent calcite crystals, each about 2 centimeters across, unusual for this locality. Another interesting find that someone told me about was an approximately one inch long mass of molybdenite in matrix. More typical finds included epidote in dark green blades up to about an inch as well as some transparent yellow-green micro-crystals. No doubt some clinozoisite was also collected, though none that I observed. And finally, as at just about every crushed stone quarry in the Maryland Piedmont, there was pyrite, mostly massive, sometimes in small octohedra, occasionally with associated minor chalcopyrite.