Natural/Volcanic Glass

Glass that is formed by volcanic action is called obsidian and can be found in many parts of the world. Obsidian is formed when the intense heat of a volcano fuses masses of silica together, forming the hard glass. Because of natural impurities, it is usually shiny, black, and opaque, but it can also be very dark red or green; its splinters are often transparent or translucent. Obsidian can be chipped and flaked to make arrow and spearheads, knives, and razors. Humans probably began to use this natural material to make tools as early as 75,000 B.C. As millennia passed, obsidian became valued for ornamental and ceremonial purposes. Although other objects were produced, it was usually fashioned into tools and weapons. It was highly valued and locations of sources were often closely guarded secrets. Ancient Egyptians imported obsidian from the region we call Turkey and perhaps even from what we call Iran.

Tektites are rounded, indefinitely shaped glassy objects thought to be a result of meteoritic impact on either the earth or the moon. Tektites are found in Czechoslovakia, Indonesia, Viet Nam, Australia, the United States, etc.

Libyan Desert Glass is found in the Sahara Desert in large sand dunes. The slightly yellowish lumps were probably created by meteoritic impact.

Lightning can create glassy formations when it strikes a sandy area with the right combination of minerals. The resulting crude, brittle, slender tubes are called fulgurites.

Just as some animals ingest calcium to form their skeletons, some microscopic sea animals such as diatoms ingest dissolved silica from seawater to form their skeletons. Huge deposits of the countless skeletons of these animals account for the mining of diatomaceous earth.