2007-07-13 17:19:56 · 3 answers · asked by willie k 2 in Science & Mathematics ➔ Earth Sciences & Geology
Chert is a A variety of silica that contains microcrystalline quartz... or a siliceous rock of chalcedonic or opaline silica occurring in limestone.
2007-07-13 18:17:01 · answer #1 · answered by Kristenite’s Back! 7 · 2⤊ 0⤋
Chert is a glassy rock associated with limestone, composed primarily of cryptocrystalline sillica (i.e. crystals that are too small to see). It commonly appears as tabular layers or nodules (often filling in trace fossils).
The source of the silica that forms chert is thought to have two main origins. The exoskeletons of Radiolaria (leading to radiolarian chert - also known as Jasper), also the siliceous spicules of sea sponges.
Due to the extremely fine grained nature, chert breaks with a conchoidal fracture. It was this property that enabled ancient man to use chert to create arrow heads, axes etc. It has also been used extensively as a building material - therefore a very useful material throughout man's history.
Chert may take on various colours, red for example may be attributed to iron oxide (Haematite) being present.
2007-07-14 02:06:07 · answer #2 · answered by Anonymous · 0⤊ 0⤋
Over here in england we get flint in limestoen and chert in chalk (cretaceous limestone) it is composed of silicon dioxide SiO2 . some of which comes from the spines of sea urchines! the sio2 dislves in water during lithification (forming of rock) and flows along and concebtrates in to lumps which make chert, badly explained i,m afraid but hope you get the jist.
2007-07-14 06:17:30 · answer #3 · answered by Will T 4 · 0⤊ 0⤋