Rockin the Rockies

Rockin the Rockies
Stowe Mtn

Monday, June 3, 2013

Field Trip for Tourmaline

Tourmaline in the Rockies can be found, but is often not the real gemmy crystals that people make jewelry out of or sell for big money. As a crystal collector I find the form and luster of tourmaline/schorl desirable NaFe2+3Al6(BO3)3Si6O18(OH)4
We had an old time crystal hunter rejoin our crystal club. He brought in a number of well formed and terminated schorl crystals. They ranged from pencil to thumbsize in thickness and a couple crystals exceeded 3 inches. Well, we got excited about that and so he helped lead a field trip to the site. When we got to the spot near Badger Mtn, he said he hadn't been there since the early 70s and had dug out most of the schorl. Oops, would have been nice to know this ahead of time. Anyway, we gave it a shot. Soon we found garnets. The garnets were fairly small and not gemmy, they were surrounded by mica and resided in the host quartzy pegmatite. Perhaps the garnets are almandine garnets Fe3Al2(SiO4)3, the color was brownish. I will have to look into that more. Upon careful inspection of the garnets, I noticed that there were small schorl crystals intermixed with the garnets (see picture below). Our leader mentioned that the best schorl could be found in quartz chunks. Evidently when these quartz chunks are put in a freezer the schorl will sometimes pop out. Schorl must contract more than quartz. Our leader said that schorl could also be found within feldspar, but is nearly impossible to extract without breaking the crystals. Seems to me a few pieces of nice tourmaline sticking out of the host rock is just as appealing as single tourmalines frozen out of the quartz... and so the hunt was on. My nephew Andrew won the prize and found a perfectly terminated pencil thick 2 inch long tourmaline (float). I found garnets and tourmaline shards. Perhaps tourmaline does not get along well with my crack hammer (kidding). My rockhounding friend Bob, found a broken but well terminated tourmaline. While the trip was not well attended everyone went away with something collectible. I think some more prospecting in the area might turn up a better spot that has not already been prospected quite so much. Until then its back to Lake George for smoky quartz and amazonite!

Looking for float or debris late in the day... somewhat relaxing pose


Andy and I watching my nephew pull out tourmaline pieces

Fragmented tourmaline resting over garnet on matrix

Dime-size garnet


One of Bob's tourmaline finds



1 comment:

  1. If broken beyond repair, it's cab or intarsia grade!

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