Mathew Lippincott has been collecting and posting research on low-cost approaches to silica detection; I saw this exhibit showing sheets of mica under a spinning polarizer, which was pretty cool. I thought perhaps there might be some way to spin a polarizer in front of a smartphone camera and measure the intensity signal over time, maybe in multiple color channels, to detect silica dust. Half-baked thought.
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In my silica wiki page, I mentioned polarized light microscopy as a detection method, and yes, I'm looking into it.
What you see here is polarized light running through the mica and then through another offset polarized filter. thats where the color comes from. a single polarizing filter won't do this, you need the two stage pass through. The color is indicative of the stress in the material. here you can see it in polystyrene:
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Great, also linking back to this prior post! https://publiclab.org/notes/mathew/04-22-2014/frac-sand-mining
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