Eventually these minerals are redeposited, or precipitated, when the water evaporates away or when the water becomes over-saturated. The process that changes the chemical makeup of a rock or mineral at or near the Earth's surface. Compare with mechanical weathering . . A very fine-grained sedimentary rock made of quartz. Usually made of millions of globular siliceous skeletons of tiny marine plankton called radiolarians.
Black chert is called flint.
Some mineralogists include chorites in the mica family because the crystals form small flakes. A family of platy silicate minerals that commonly form as a product of rock weathering . Cobbles are a size of gravel larger than pebbles, but smaller than boulders. . Along with cementation, this process converts sediments to solid rock. Such a convergence between the Indian and Eurasian plates is responsible for producing the Himalayas. .