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