PYROPHYLLITE: TUCSON GEM SHOW REPORTS: MINERS CO-OP

My next daily journey took me to the Miners Co-op Rock Show, a venue now in its second year.  Many of the Co-op vendors were once at the Kino venue; however, the Kino soccer fields are now off limits to sellers and many migrated to this new area.  I enjoy the Miners Co-op since it is the “genuine thing” of small-time vendors selling from tents and pickup beds or piles emplaced on tarps with their small camping trailers circling the area.  A tamale vendor wanders through the tents around lunch time and an older model pickup drives around selling water from a large tank in the bed.  Mom and pop operations at their finest.  In addition, I recognized some of the vendors as members of the Colorado Springs Mineralogical Society, while others were from nearby towns.

The tents often were not large enough to cover the specimens on the tables from the massive weekend rains.

Large specimens were often just placed on large plastic tarps.

I love the mixture of minerals, jewelry, used lapidary equipment, and whatever “for sale” at a variety of venues.  Note the straw placed around the booths after the recent rains.

I really do not like to observe the sale of Native American artifacts like there pot shards. 

My “$5 or less” mineral of the day is pyrophyllite, actually a “real buy” at $1.  I have sort of been fascinated by this aluminum silicate hydroxide [Al₂(Si₄O₁₀)(OH)₂] since first observing the radiating masses coming out of Graves Mountain, Georgia.  Although the best collectable specimens are these aggregates of radiating needles, pyrophyllite also occurs as massive grains and folliated laminar masses.  The silicate layers give it a nice cleavage.  It is a very soft mineral, ~1.5-2.0 (Mohs), with a pearly luster, somewhat transparent in the non-massive form, and found in a variety of earth-tone colors: brown, green, gray-white, brown-yellow, gray. 

Radiating silver-brown rosettes of pyrophyllite from Graves Mountain, Lincoln County, Georgia.  Width ~4.5 cm.

Pyrophyllite is isomorphous with talc and almost has identical physical properties; both are monoclinic, however, talc has magnesium substituting for the aluminum.

Pyrophyllite may be found in a few hydrothermal rocks; however, most occurrences are in low grade metamorphic rocks where it usually is an alteration product of kyanite [Al₂SiO₅].  The Graves Mountain specimens are especially attractive stellate aggregates.