The Post Up a Rock on Tuesday thread.

Fulgurites are formed when lightning with a temperature of at least 1,800 °C (3,270 °F) melts silica or other common conductive and semiconductive minerals and substrates, fusing, vitrifying, oxidizing and reducing mineral grains and organic compounds;[6] the fulgurite mass is the rapidly quenched end-product.

The temperature peak within a lightning channel, however, is known to exceed 30,000 K, with sufficient pressure to produce planar deformation features, or "shock lamellae" in SiO2 polymorphs. It is assumed that the process of forming a fulgurite occurs over a timespan of the order of a single second, following the termination of the return stroke.

Fugerites are commonly hollow and/or branching assemblages of glassy, protocrystalline, and heterogeneously microcrystalline tubes, crusts, slags, vesicular masses, and clusters of refractory materials that often form during the discharge phase of lightning strikes propagating into silica-rich quartzose sand, mixed soil, clay, caliche and other carbonate-rich sediments.

“ Type IV - rock fulgurites, which are either crusts on minimally altered rocks, networks of tunneling within rocks, vesicular outgassed rocks (often glazed by a silicide-rich and/or metal oxide crust), or completely vitrified and dense rock material and masses of these forms with little sedimentary groundmass.”

Jean Baptiste Charbonneau
1805–1866
This site marks the final resting place of the youngest member of the Lewis and Clark Expedition. Born to Sacagawea and Toussaint Charbonneau at Fort Mandan (North Dakota), on February 11, 1805, Baptiste and his mother symbolized the peaceful nature of the "Corps of Discovery." Educated by Captain William Clark at St. Louis, Baptiste at 18 traveled to Europe where he spent six years becoming fluent in English, German, French and Spanish. Returning to American in 1829, he ranged the far west for nearly four decades as mountain man, guide, interpreter, magistrate, and forty-niner. In 1866, he left the California gold fields for a new strike in Montana, contracted pneumonia en route, reached "Inskips Ranche" here, and died on May 16, 1866.