Jon surmises that he's collected at Hunting Hill a couple hundred times. "Before OSHA," he recalls, " you could just sign a waiver at the gate to go in and collect." Today the quarry grants access only by pre-arrangement at specified times exclusively with clubs and groups that carry insurance. Jon is an active member of both the Montgomery County Mineral Society and the Northern Virginia Mineral Society, which share Hunting Hill as their most popular field trip destination. No other Maryland locality yields such a wide variety of minerals, 69 at last count. Hunting Hill is the only Maryland locality for many of these species. Some, such as pokrovskite and xonotlite, rarely occur anywhere else in the world.
Jon also takes pride in his suites of minerals from such no longer accessible Northern Virginia localities as Centreville Quarry, Bull Run Quarry, Luck Quarry, Chantilly Quarry, and Goose Creek Quarry. His collection also holds an enormous quantity of worldwide minerals. They dominate the inventory he sells at regional swaps and shows, although he emphasizes that every mineral in his collection is for sale.
Notwithstanding,
Jon's Hunting Hill grossular garnets reign supreme. Displays such as pictured at left are prominent in his sizeable basement. Hundreds of smaller pieces, including plenty of thumbnails, fill flats lining the wall. The crystals typically ocur in a serpentinite-rodingite matrix and sometimes associate with very attractive light
green clinochlore crystals. Of all the Hunting Hill garnet pieces in Jon's collection, his favorite is the one pictured at right. For aesthetics and quality, he sees it as representing the best of a classic genre. He'll sell it for $1000. If that's too much for the budget, plenty of very attractive smaller pieces go for less than $10.
Jon has sent some of his Hunting Hill garnets to Thailand for faceting. He charges about $80 a carat for these cut stones and is in no big hurry to sell them. Yours truly may have been among the first to get in on this one. Pictured at right is my wedding ring, in the center of which a Hunting Hill garnet that Jon collected has replaced the original However unusual my ring, I have yet to see any jewelry bearing Patuxent River agate. Maryland's legislature chose this alleged manifestation of silicified dinosaur bone a few years ago as the State's official gemstone. Confident that most Maryland jewelers, geologists, and members of the rockhound community agree with him, Jon Ertman proclaims they should have picked Hunting Hill garnets.
Jon can be reached at grossular9@live.com.




Orthominasragrite: This extremely rare vanadium sulfate accompanied by acicular white rozenite was discovered by Pat in a silicified tree fossil at the North Mesa 5 Mine, Temple Mt., Emery County, Utah. It is the orthorhombic polymorph of minasragrite for which the type locality is the Ragra Mine (minasragra) in Peru. It occurs only in crystalline microscopic crusts.
Bobjonesite: Pat insisted that this third vanadium sulfate he discovered at the North Mesa 5 Mine remain in its container to be photographed. Named by Pat to honore the eminent mineralogical speaker and writer, and editor of Rocks and Gems, Bobjonesite is stable only in extremely dry atmosphere and quickly hydrates when exposed to air. Because it has only three waters in its structure as opposed to five waters in the other vanadium sulfates, a synthetic equivalent was used during analysis to determine the x-ray powder diffraction pattern.













