Check this piece of petrified wood out I found along the river. I recently upgraded to a much stronger and efficient UV flashlight. My previous ones worked at 395 NM wavelength, whereas the new one operates at 365 NM wavelength, eliminating a lot of the unwanted purple light that the older models gave. Lots (but not all) petrified wood will react to UV light. It depends on how much phosphors are present in the petrified wood matrix. Any rock hounds out there to compliment metal detecting?
