Here is an entire vial of petroleum included 4 phase Quartzes. I would estimate there are at least 30 individual crystals. They fluoresce like crazy, and otherwise have a golden yellow hue under natural light. I will also throw in a 60X power handheld microscope with both natural light LED and long wave Fluorescent LED free of charge (a $12 value). 

It is a four phase inclusion in a double terminated Quartz crystal found in central Pakistan 6 years ago. It is highly fluorescent under both short wave and long wave (LW pictured). The long wave makes the petroleum fluoresce yellow, the short wave brings out the more reds and blues. The gas bubble forms when the the Quartz cools after forming, the petroleum contracts more than the Quartz because it is less dense, it pulls a vacume within the fluid thus creating a "gas" bubble.  The four phases are: the gas bubble trapped in the petroleum, the petroleum itself, a darker brown previously organic material, and black carbon inclusions. I learned this from an insightful geologist who specializes in Quartz inclusions, whom I met at the Tucson Main show.