However, fulgurite, a glassy tube-like, crust-like, or irregular mineraloid that forms when lightning fuses soil, quartz sands, clay, rock, biomass, or caliche is prevalent in electrically-active regions around the globe and provides evidence of not only past lightning activity, but also patterns of convection.
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Its chemical formula is Al 2 O 3 ?( SiO 2 ) 1.3-2 ?( 2.5-3 ) H 2 O . Since it has short-range atomic order, it is a mineraloid, rather than a mineral, and can be identified by its distinctive infrared spectrum and its X-ray diffraction pattern.
