My cheap UV flashlight trick for spotting certain minerals

Nina Schmidt · 2026-04-04T10:25:04.360642+00:00

I was sorting a big box of mixed rocks from a trip to Arizona and couldn't tell some calcite pieces from plain quartz. I had a cheap UV flashlight from a Halloween costume, the kind that uses 3 AAA batteries. On a whim, I turned off the lights and shined it on the pile. The calcite pieces glowed bright orange, but the quartz was totally dark. It made sorting them out super fast. Anyone know other common rocks that light up under UV?

wrenwilson5mo ago

@linda_butler28 I used mine on fluorite, glows blue.

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linda_butler285mo ago

Wait, you just had a UV flashlight lying around from Halloween?

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piper1752mo ago

Huh, @wrenwilson thats a good one about fluorite but have you actually tried it on willemite or scheelite? Those two go nuts under shortwave UV, especially scheelite it glows a bright bluish white thats hard to miss. I picked up a cheap UV flashlight from a hardware store for checking coolant leaks and it worked fine on calcite too but you gotta be careful because some of those cheap ones put out a pretty wide spectrum and can miss certain minerals. What kind of UV bulb was in that Halloween light you were using?

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