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Last month, I had the pleasure of visiting the very accomplished veteran Pennsylvania field collector who unearthed that sulfur crystal at the Jacksonville Quarry in Centre County. In the company of his his wife Jeanne as well as other prominent Pennsylvania collectors, Joe Dague has been at it for decades.
Although the primary purpose of my visit was to see some of the pieces he had picked up on outings to Maryland a few miles south from his Chambersburg quarters, Joe's Pennsylvania specimens distracted me. Not that he didn't have plenty of great Maryland material, which we will be covering on one of two related posts in the coming months.
Since his Maryland minerals were packed away in flats, some of the first mineral specimens Joe showed me were in a small cabinet bearing thumbnails. Upon its shelves were more interesting and unusual Pennsylvania minerals than I could even begin to digest.
How about tyorlite from the McCauley Prospect #17 near Franklin Township in Lycoming County, PA? To my knowledge and according to all that's posted on Mindat, this is the only locality in Pennsylvania from which tyrolite was ever reported. Sometime after that discovery, about 30 years ago, someone bulldozed the McCauley Prospect dumps back into its pit, which has long grown over. 
Another piece that instantly amazed me was a specimen of enargite altering to conichalcite and cornubite shown at right. Joe collected this from the Lime Bluff Quarry near Muncy, also in Lycoming County.
Grabbing me no less was that green sphalerite at left from the Thomasville underground limestone mine Jackson
Township in York County. This specimen came from a find in 1990 by the preeminent Pennsylvania field colletor Bryon N. Brookmyer. When Wendell Wilson, Editor-in-Chief and publisher of Mineralogical Record saw these specimens, he proclaimed them the best green sphalerite he'd ever seen.
In addition to all the rare, unusual and regional species he and Jeanne have collected in the field, their worldwide wurtzite suite could be the best anywhere. It's Joe's favorite species. He explains why:
Jeanne and I collected the wurtzite specimen (pictured at right) about twenty years ago at a coal strip mine in Elk County, Pa. I'm especially fascinated by the wurtzite mineral species because the marine shales overlying the Brush Creek and Vanport limestones in western Pennsylvania are the type localities for three wurtzite polymorphs--4H, 6H and 15R. For natives of Western Pa. such as Jeanne and me, wurtzite remains one of the very few interesting minerals that collectors can find in the old abandoned strip-mine in that area. In addition to several Pennsylvania sites, we now have wurtzite specimens from 17 localities worldwide.Another Dague specialty is kimberlite, especially Pennsylvania kimberlite, of course. While no Pennsylvania kimberlite is known to bear diamonds, as it does in Arkansas, Pennsylvania is well known for two kimberlite dikes. The first is the Gates-Adah Dike, which is located in an outcrop along the Mongonahela River where Fayette and Greene Counties meet. The other, the Dixonville-Tanoma Dike is beneath the earth in the Tanoma Coal Mine. Pictured below at left is a kimberlite specimen from a THIRD! little known Pennsylvania kimberlite dike.An image of it appears below at left. Per Joe, here's the scoop:
(It's) a rock sample of the third known kimberlite dike in Pennsylvania--the Ernest mine kimberlite. Jeanne and I collected this sample on August 22, 2009. Our find of this specimen confirmed its previously suspected existence, and it is now the third known kimberlite dike in western Pennsylvania, and the first to be discovered here in nearly a century.And that's not all. While my research may not be exhaustive, it's clear that little if anything has been written regarding a kimberlite dike existing in Maryland. Regardless, Joe showed me and allowed me to photograph for publication here a specimen of Maryland kimberlite. Please stay tuned on this one. It will be the subject of yet another subsequent post in several months.
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