With my newly free time I am getting back to tools I got for the book. One of these is the 65 pound microscope sitting on my computer desk.
I have just been looking at a vial’s worth of sand bought recently in Goldfield, Nevada. The consulting geologist William Vanderford sold it to me from his shop, Vanderford’s Gold Strike.
Vanderford has traveled the entire West. This vial bears a hand written label. “Corundum sand, Sapphire Mountains, Philipsburg, Montana.
Corundum sand is extremely hard, at 9 on the Mohs Hardness Scale, just below diamond. It’s often used as an abrasive. I
It’s possible this sand came from this fee dig:
The photo below is what you’d see with a 10X hand lens.
The next photo gets closer to the same spot.
And closer still. I haven’t figured out yet how to express the microscope’s settings in terms of power. Like, “This photo was taken at 100X.” I’m still new to this.
The next photo is high power but on a different spot.
I didn’t see anything as nice as what is shown at sandatlas.org. They describe the best grains as having, “The typical crystal shape of corundum — elongated crystals that are widest in the middle and have hexagonal cross-sections.”
Nothing hexagonal right now. I’ll try looking more later. Takes some time to go through sand grain by grain.
My sand is too worn by stream tumbling to identify what I am looking at. If this location was anywhere elsethan the Sapphire Mountains, I’d think my clear pieces are mostly quartz, the red mostly garnet.
The photo below shows conchoidal fracture in a grain of sand. Kind of neat. That’s how all quartz fractures, from most petrified wood, most agates, and anything known as chalcedony. Trouble is, corundum, garnet, and sapphire all fracture in this manner, not just quartz.
This next photo shows a few crystal faces, the rest of the grain badly weathered or eroded. You can tell a crystal face by the flat surfaces and the opposed angles that go out in an ordered manner. Quite unlike the edge produced when a rock simply breaks apart.
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