Day #105 Deskcrop: More Black Hills Staurolite Schist

Mmmm, staurolite! One of the loveliest porphyroblasts – particularly when twinned (see the left end of today’s deskcrop, below), staurolite is the metamorphic index mineral above garnet in the progressive metamorphic sequence in metapelites. This particular sample has a more schistose texture than the staurolite schist I previously featured, and comes from a bit more remote locality.

When I collected this one back in 2003 web-based mapping tools were still in their infancy. Nonetheless, I have a distinct memory of planning the search for this locality with them and printing out a bunch of satellite images of this area of the Black Hills to aid my back-roads navigation. Today I can do all of that on the fly, in the field, and in real time on my Motorola/Verizon Droid cellphone. Oh, how times have changed!

The kyanite zone is up next, with a deskcrop from Wisconsin…

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Staurolite Schist, Black Hills

Explore this and all of my 2010 Deskcrops and Outcrops in Google Earth!