Get off the beaten path... If you want to find those mom-and-pop joints, those funky little places, just ask around. Guy Fieri
Funky little rock shops where everyone wears a mask!
I often bemoan the fact that certain items are disappearing from the American roadside, things like drug stores with ice cream and shakes, general stores, non-chain hamburger stands, and especially “mom and pop” rock/mineral/fossil stores. I suppose that my age and nostalgic thinking make these disappearances seem severe when in reality you can order any mineral that pops into your mind from a web business (now ice cream is a little tougher). But there is, to me, something special about pulling open a dusty drawer in an old cabinet and taking a lighted loupe to examine a dusty specimen with old hand-written labels. I am always on the lookout for these stores and make an attempt to locate and patronize these establishments. On the other hand, it is tough to make a living selling minerals for a buck or five and most of these stores seem a labor of love.
I recently took a little road trip and stopped at one of my favorite old timey stores and begin sneezing while blowing dust off some of the drawer specimens—not many other tourist patrons bother with the drawers. Not really needing any new minerals, I still made a purchase of some interesting specimens at “cheap” prices. So, what little jewels did I come home with (only a partial list)?
The very reason I collect and write about minerals is so I might not sleepwalk through my entire life. Apologies to Zadie Smith
Bisbee, Arizona, is known to rockhounds and mineralogists through the world. The Copper Queen Mine and the Lavender Pit Mine have produced an array of secondary copper minerals that are considered classics. Rock and mineral shows have devoted their attention and themes to Bisbee minerals. And virtually any mineral collection, at least here in the states has a beautiful specimen of blue Bisbee azurite and usually one of green malachite. However, I needed something new from Bisbee and spotted a thumbnail with antlerite, a copper sulfate hydroxide [Cu3(SO4)(OH)4]. Antlerite is found as a secondary mineral in the carbonate-poor, oxidized zone at many copper mines but is never common. In fact, Anthony and others (1995) noted it was rare and in mines of the Bisbee area was collected from the Copper Queen Mine (probably) as small crystals of excellent quality implanted on brochantite. Antlerite ranges from emerald-green to light green to blackish green in color. Crystals are vitreous, translucent, brittle and soft (~3.5 Mohs) and leave a pale green streak. Most crystals are thick tabular, or equant or short prismatic. They also occur as rather non-descript granules or aggregates of fibrous crystals.
By the time mineralogy class rolled around students were introduced to a variety of garnets and learned that “garnet” was not a legitimate mineral name but referred to a group of silicate minerals differing in composition but crystallizing in the same system (Isometric), and their mineral properties such as hardness, cleavage and density were all very similar. Usually the specimens studied were almandine [Fe2+3Al2(SiO4)3], pyrope [Mg3Al2(SiO4)3], spessartine [Mn2+3Al2(SiO4)3], andradite [Ca3Fe3+2(SiO4)3], and grossular [Ca3Al2(SiO4)3]—all end members in the Garnet Group. Things got more difficult in graduate-level courses in igneous and metamorphic mineralogy/petrology and instructors added uvarovite, also an end member, [Ca3Cr2(SiO4)3] to the list for study. Chemical formulae for members of the Garnet Group is X3Y2Si3O12 where X includes the divalent (2+) oxidation charge cations like Ca, Mg, Fe, and Mn while Y represents trivalent cations (3+) oxidation charge like Al, Fe, and Cr; all cations are clustered around the silica tetrahedra. Today MinDat lists 14 different minerals belonging to the Garnet Group with many of these types having numerous varieties. For example, spessartine has at least six varieties while grossular parades out 15 varieties including the popular, and expensive, green tsavorite with coloring supplied by chromium and vanadium. Garnet Group members have two solid solution series: 1) pyrope-almandine-spessartine; and 2) uvarovite-grossular-andradite. Essentially all colors of the rainbow are present in some variety of garnet since rare blue colored specimens were discovered a couple of decades ago.
At the rock/mineral shop I picked up a small cluster of andradite crystals. This species has three major varieties: melanite (black), topazolite (yellow-green), and the uber expensive demantoid (green). My find of mineral store garnet crystals is the rather unusual andradite variety termed melanite or titanium garnet. These are black garnets where the titanium evidently replaced or comingled with the silicon since the titanium (up to ~11%) appears as titanium oxide. The crystals are dodecahedrons with an adamantine luster and a hardness of ~6.5-7.0 (Mohs), and a white streak. They are pretty opaque but will partially transmit light from a rear source. Unlike other garnets that usually form in metamorphic environments, melanites with their titanium often form in alkaline igneous rocks (low silica), but also in serpentine, skarns, crystalline schists, and iron ores. The locality information, simply “New Idria Mining District, San Benito, CO, California.” This District is famous for world class benitoite, neptunite, topazolite and melanite andradite garnets. I believe the garnets formed in a skarn, a metamorphosed limestone intruded by hydrothermal solutions heated by nearby intrusions.
The Spruce Pine Mining District in North Carolina is one of the best-known mining areas in the U.S. It is in a beautiful area of the Blue Ridge Mountains centered in Mitchell and Yancy Counties and mineral-wise is famous for gem specimens of beryl--varieties aquamarine, emerald, heliodor, and morganite. North Carolina is the country’s largest producer of feldspar and original mines centered near Spruce Pine and produced from a Precambrian pegmatite; however, current production is from “alaskite” (a variety of granite) described as a very “coarse-grained, light-colored, feldspar-quartz-muscovite rock. Composition of the rocks averages about 40 percent plagioclase (soda-spar), 25 percent quartz, 20 percent microcline (potash-spar), and 15 percent muscovite” (information gleaned from North Carolina Geological Survey at deq.nc.gov). The Spruce Pine area is also the major producer of sheet mica, scrap mice and olivine in the U.S., as well as a number of other industrial minerals.
The specimen I picked up is an intrusive igneous rock with various feldspars, schorl (a black tourmaline), quartz, and a nice golden beryl crystal that was collected from the Ray Mica Mine near Burnsville in Yancy County. I have been through Burnsville a few times on my way to lodging in Little Switzerland, and while traveling along the Blue Ridge Parkway, a scenic 469-mile road running near the crest of the Blue Ridge and connecting Great Smoky Mountain National Park in the South and Shenandoah National Park in the north. The Blue Ridge is the high part of the Appalachian Mountains with a variety of crystalline rocks emplaced during continental collision and subduction generally termed the Grenville Orogeny or the Grenville Cycle. At any rate, the Grenville was not one major event but a series of orogenic phases from ~1250 Ma to ~980 Ma, or somewhere around there, with the end result being the formation of the Supercontinent Rodinia. There were additional granite emplacements somewhere around 700 Ma due to rifting of Rodinia. The Paleozoic history of the Blue Ridge and the Appalachian Mountains is a “whole nother story.”
Golden beryl. Top: length ~1.6 cm.; width of hexagonal end ~7 mm.
Cluster of schorl crystals. Width FOV ~1.9 cm.
I enjoy it; my experiences in traveling and looking at the rocks have taught me the importance of an open mind and have given me a willingness to wander off the beaten path - not only to keep life interesting, but also to understand in a meaningful way that things do not look the same from every vantage point.
Apologies to Esther Dyson
Anthony, J.W., S.A. Williams, R.A. Bideau, and R.W. Grant, 1995, Mineralogy of Arizona: The University of Arizona Press, Tucson.