Maryland Mineralogy Presented at Rochester Symposium

• Note: Readers are encouraged to check out the Mineral Bliss Podcast about the Rochester Symposium.

Beyond the State or local level, a presentation such as Fred Parker delivered on the morning of April 16 at the Rochester Mineralogical Symposium has long been overdue. As Parker expressed early in his talk, Maryland is "the Rodney Dangerfield of the mineral world." He also credited amateur Maryland geologist Jeff Nagy for much of the presentation's information and perspective. Nagy and Parker have been working together on research intended for an updated printing of Lawrence R. Bernstein's Minerals of the Washington, D.C. Area, which was originally published in 1980 by the Maryland Geological Survey.

The presentation was in three parts as follows:

• A short history of mining in Maryland


• Review of a geological map of Maryland


• A slide show of relevant Maryland Minerals
  

MINING HISTORY

Despite reports that Captain John Smith recognized the presence of bog iron ore in sedimentary deposits near the Chesapeake Bay, mining did not begin in Maryland until 1740 with patents for iron and copper. Thereafter, Maryland mined iron in substantial quantity, some that was used in the manufacture of munitions during the American Revolution. Pre-revolutionary dumps are still accessible at Mineral Hill in Carroll County. Maryland was also a significant producer of iron for the War of 1812

By the 1840's, Maryland had become one of the world's leading producers of chromium. The ore was mined at Bare Hills and Soldiers Delight in Baltimore County, near Cooptown in Harford County, and near the Pennsylvania State Line in Cecil County. Soon after the Civil War, Maryland was also a source, though never on a major scale, for a variety of other metals including gold, lead, manganese, and zinc. An accompanying slide, possibly the only known photograph of a facility in Maryland where metals were mined, pictured a manganese operation along the Potomac River about five miles upstream from Harpers Ferry. Maryland also produced such nonmetallic materials as mica beryl, feldspar, clay, talc, and coal.

MAP OF PERTINENT GEOLOGY

A map with colors explaining the geology inherent to the state's rock forming minerals was the focus of the presentation's second segment. It emphasized Maryland's central portion, which is more favorable to the pursuit of mineralogy than the coastal plain to the east or Garrett County at the western end of the state. Parker noted the following:

• Formations of diabase still being quarried along the Susquehanna River near Havre de Grace.
• Serpentine deposits that appear and reappear in a northeast to southwesterly path from the State Line in Cecil County in the northeast to Montgomery County in the southwest with reappearances in Harford, Baltimore, and Montgomery Counties.
• Miocene sediment deposits along the Patuxent and also the Potomac Rivers that have yielded an abundance of high quality gypsum crystals.
• The Baltimore gneiss, a metasediment that occurs sporadically in more spots than could be shown on the map. The Baltimore gneiss hosts many pegmatite intrusions that Parker described as "really quite fascinating in Maryland."
• The Wakefield Marble accounts for both the active Medford and Portland Quarries in Carroll County as well as the long closed Liberty Mine in Frederick County, once Maryland's biggest producer of copper.
• Parker noted the existence of Paleozoic sediments between the Wakefield Marble and the Precambrian metavolcanic Catoctin and Braddock mountain ranges. He described the latter as the source of excellent quartz veins near where these mountains approach the Potomac River.
• Immediately west of the mountains is a region of limestone, shale, and sandstone extending into Pennsylvania and Virginia. It is the source of similar minerals in all three states.

SELECTED MINERAL OCCURRENCES IN MARYLAND

This was the most extensive segment of the presentation. The minerals were shown pursuant to their localities in conjunction with the geological map. Most can be seen on the Picasa slide show at the Maryland Minerals web site. Some, of these minerals also appear in posts on this site from July 18, 2009, May 2, 2009, and April 25, 2009 . Here are some of the highlights noted:

• Approximately 250 different mineral species have been collected in Maryland.
• Maryland is the type locality for one mineral, carrollite, which was discovered at the Patapsco Mine in Carroll County, for which it is named.
• Significant quantities of tourmaline (variety schorl) showing several different habits including terminated crystals up to six inches in chlorite schist have been collected at the Maryland Materials Quarry in the diabase formation along the Susquehanna River.
• As noted in the geological segment, the Miocene sediment deposits at Chancellors Point in St. Mary's County and Fort Washington in Prince Georges County have produced gypsum crystals of magnificent quality.
• Garnets up to two inches in chlorite schist are abundant in a wooded area of Baltimore County about 22 miles north of Baltimore City.
• What Parker belives could be Maryland's most prolific beryl locality is on the banks of a river near the Baltimore/Howard County line at a locality that he and Nagy refer to as the "Waterside Prospect." It is currently covered with water.
• A particularly interesting slide showed monazite, which is rare in Maryland, from one of several long closed mica mines in Montgomery County.
• Another slide displayed quartz crystals from a "lost" locality in Clarksville, Howard County, which Parker rediscovered when combing the digs for a housing development that ultimately obliterated the locality.
• One of the most spectacular slides was of an historic botroydal malachite specimen from Carroll County's Patapsco Mine.
• Two slides of Maryland gold in quartz, one from Montgomery County, another from Carroll County, attracted major interest.
• Parker cited the Medford Quarry in Carroll County as Maryland's most prolific locality. He emphasized its abundance of diverse calcite pockets and also noted it as the source of some rare minerals. As an example, a slide of micro lanthanite crystals from a one-time find was shown.
• The Portland Quarry at Union Bridge in Carroll County, just a few miles from the Medford Quarry, received the distinction of being Maryland's most unpredicable locality Among the slides with which Parker demonstrated this point was one of a transparent yellow wulfenite specimen from a find in the 1970's.
• Predictably and appropriately, he reserved for the Hunting Hill Quarry in Montgomery County the honor of being Maryland's most mineralogically important locality. Citing the gemmy grossular associated with its serpentine and rodintine, he compared Hunting Hill's geology to Vermont's Eden Mills locality. He then showed slides of some of the seventy one different species that have been collected at Hunting Hill. A slide of xonotlite crystals was particularly noteworthy.
• An expecially spectacular slide showed quartz crystals that were collected in the soil near Burkittsville in Frederick County prior to the Civil War.
• Further west in Paleozoic limestone near Hagerstown in Washington County, Parker noted that one of several quarries that are quite similar to one another has produced attractive strontianite as well as native sulphur and celestine.
• Further west in Washington County, Parker recognized the Pinesburg Quarry for its blue barite crystals and showed a slide of an exceptional specimen from his personal collection.
• The final and westernmost locality he named was Savage Mountain near Frostburg. Once mined for its fire clay, it was one of Maryland's most popular collecting localities in the 1930's and 1940's. Savage Mountain is best known for geode like nodules filled with crystals of siderite and barite. A highlight was a slide photographed by Yours Truly of such a nodule bearing spectacular needles of millerite up to an inch long.
• Parker concluded his presentation with an image of that he described as a "doorstop," namely serpentine and chromite with an historic label attached to it. The idea was to make the point that despite the initial impression of numerous mineral people, Maryland's mineralogy amounted to more than than simply these two species.

Note to readers: The next Mineral Bliss post is scheduled to appear at the end of the second week of May, 2010