Chert is a hard, fine-grained sedimentary rock composed of microcrystalline or cryptocrystalline quartz, the mineral form of silicon dioxide (SiO2). Chert is characteristically of biological origin, but may also occur … See more

Chert is of only modest economic importance today as a source of silica (quartz sand being much more important.) However, chert deposits may be associated with valuable deposits of iron, uranium, manganese, phosphorite, and petroleum See more

• Petrology – Branch of geology that studies the formation, composition, distribution and structure of rocks
• Archaeology – Study of human activity based on materials that people have left behind. See more

In petrology, the term "chert" refers generally to all chemically precipitated sedimentary rocks composed primarily of microcrystalline, cryptocrystalline and microfibrous silica. Most cherts are nearly pure silica, with less than 5% other minerals (mostly See more

The cryptocrystalline nature of chert, combined with its above average ability to resist weathering, recrystallization and metamorphism has made it an ideal rock for preservation of … See more

There are numerous varieties of chert, classified based on their visible, microscopic and physical characteristics. Examples are: See more

• Photo & note re: Fig Tree Formation
• Microphotographs of Fig Tree fossils
• Schopf, J.W. (1999) Cradle of Life: The Discovery of Earth's Earliest Fossils, Princeton University Press, 336 p. ISBN 0-691-00230-4 See more