The scattered white rocks of the Sierra

A place to explore the natural setting (geology, flora & fauna), people, constructed infrastructure and historical events that play and have played a part in shaping the Sierra Nevada as we know it today.
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giantbrookie
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Re: The scattered white rocks of the Sierra

Post by giantbrookie » Sat Mar 28, 2020 6:55 pm

What is pictured is quartz and this is what forms most whitish transparent/translucent rocks, veins, etc. in the Sierra. At times there are potassium feldspar pegmatites in which there are whitish somewhat cube-shaped crystals of k-feldspar (and somewhat more transparent quartz that looks darker in comparison). Some of those pegmatites have big flakes of mica (once found them as big as the palm of my hand), and/or they may have black tourmaline. One such vein, somewhere in the East Sierra, that I stumbled upon in the mid 90s has stunning deep dark blue sapphire (hexagonal cross section). In other places you see big white veins, they may be calcite, especially in areas where you have a lot of marble or limestone. The best examples of calcite veins are in the Convict Canyon area. They once mined the optical quality calcite there and one can find rhomb shaped cleavage-bounded chunks as large as old-school television sets there. In the afternoon-evening light the calcite rhombs in talus glitter so that from below it is a very odd sight. Other places you can get calcite veins in the High Sierra are Dinkey Lakes and Kaiser Wildernesses, both of which have some limestone/marble in therm.


Since my fishing (etc.) website is still down, you can be distracted by geology stuff at: http://www.fresnostate.edu/csm/ees/facu ... ayshi.html" onclick="window.open(this.href);return false;






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JosiahSpurr
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Re: The scattered white rocks of the Sierra

Post by JosiahSpurr » Fri Nov 27, 2020 1:27 pm

CAMERONM wrote:
Sat Feb 15, 2020 3:19 pm
I have wondered for years about seemingly random white rocks I find in the Sierra. They can be semitransparent, and sometimes also have a brownish tinge on some facets. They almost never appear as a solid area or even a solid vein [.....]
Almost never...

"""The quartz pillow covers about four acres of ground in total. All around, it is surrounded by normal granite but due to some geologic fluke, this big square chunk of earth is solid quartz! Through the middle of the conglomeration runs a little creek. It's very cold and clear. Throughout the pillow, there are veins containing clear or Ice Quartz. Native Americans used to gather it up and trade the material far and wide."""

SEE:

http://www.springcreekllamas.com/stories/sierra2003.php

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