Firefly Quartz (also called Firefly Petroleum Quartz or Madagascar Firefly Quartz) is a trade name for a type of petroleum-included quartz from Madagascar. It’s similar to the well-known petroleum quartz from Pakistan, but with its own distinct look and structure. When illuminated under UV, these inclusions glow brightly—hence the name “Firefly.”

Madagascar Firefly Quartz frequently contains liquid + gas (and sometimes micro-crystals), moveable bubbles that dance when you tilt the crystal, these are called two-phase fluid inclusions.

They form as quartz grows around droplets of hydrocarbons, trapping a tiny gas bubble inside. Hydrocarbon-rich inclusions like these usually indicate low-temperature quartz formation, and a relatively young geological age (compared to deep metamorphic quartz).

This particular specimin happens to have a fairly large gas bubble, ask me about it and I'll show you !