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| Dumortierite-sericite schist, composed mostly of dumortierite, sericite (AKA fine-grained muscovite), quartz, and possibly andalusite. |
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| Sheen from the fine-grained, clear to white sericite (muscovite) on foliation planes and disseminated in the schist. |
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| Lavender dumortierite schist. |
Dumortierite has been mined for use in making refractory ceramics such as those used in spark plugs. It is sometimes used as a gemstone (or rock), and the blue varieties have sometimes been used to make fake lapis lazuli.
By the way, these rocks are currently unlabeled. Andrew Alden has a good post up recommending that everyone label their rocks and minerals (with name and location or provenance). I will be able to label precisely all but the reddish volcanic rock.
Related Posts:
Friday Photo: Dumortierite
The Road to the Champion Mine
Rock Walls at the Champion Mine Lower Workings
Dumortierite at the Champion Mine, Nevada
Upper Champion Mine Workings
Selected Reference:
Mackay School of Mines staff, 1928, A bulletin by the Mackay School of Mines staff on the mineral dumortierite, University of Nevada Bulletin, vol. 22, no. 2: Nevada Bureau of Mines and Geology Bulletin 8, 47 p., including 1 oversized page.
3 comments:
Interesting--Dumortierite seems to be becoming the mineral of the year. A few weeks ago someone on Andrew Alden's forum vaguely described a cobble they found on the shore of one of the Great Lakes and wondered if it could be Dumortierite. I replied that, since Dumortierite was a rare borosilicate mineral, it was unlikely, and that I had never heard of Dumortierite, so had to look it up to see what it is. Then you showed us your Dumortierite mine shortly afterward, and now a deskcrop! It's nice to see what the stuff really looks like, even if I never do see it in "the wild". Thanks for sharing!
--Howard
It is fairly rare: as of the 1928 MSM or NBMG bulletin, 7 U.S. states held known dumortierite localities: Arizona, California, Colorado, Nevada, New Mexico, New York, and Washington. It also occurs in at least one area in Ontario, and one (?) locality in Mexico.
Having seen it a long time ago at the Rochester area in Nevada, I had grown to think of it as fairly common (and easily collectible within a few hours of Reno).
So, come to Nevada if you'd like to see it in the wild! :)
Thanks for sharing beautiful stone images with us.
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