One common way in which lechatelierite forms naturally is by very-high-temperature melting of
quartz sand during a
lightning strike. The result is an irregular, branching, often foamy hollow tube of silica glass called a
fulgurite. Not all fulgurites are lechatelierite; the original sand must be nearly pure silica. Lechatelierite also forms as the result of high pressure
shock metamorphism during
meteorite impact cratering and is a common component of a type of glassy
ejecta called
tektites. Most tektites are blobs of impure glassy material, but tektites from the
Sahara Desert in
Libya and
Egypt, known as
Libyan desert glass, are composed of almost pure silica that is almost pure lechatelierite. High pressure experiments have shown that shock pressures of 85
GPa are needed to produce lechatelierite in quartz grains embedded in
granite. Lechatelierite was formed during the impact of a
meteorite into a layer of
Coconino Sandstone at
Meteor Crater in
Arizona. During the rapid pressure reduction following the impact, steam expanded the newly formed lechatelierite. The shattered and expanded glass has a density less than that of water. Lechatelierite may also form artificially, a unique example being the
trinitite produced by melting of quartz sand at the first nuclear bomb explosion at Trinity Flats,
White Sands, New Mexico. ==References==