Whetstone refers to a natural mineral sintered material. "Whetstone" is black or brown-black, exposed to the ground because of weathering and pale, the surface does not seem to contain oil, but when the hot gas distillation, the organic matter in the decomposition into kerosene, hence the name. Its fine and tough texture can be used as abrasive tools. Later, the strip consolidation abrasives made of abrasives and binders were called whetstones.

The origin of whetstone is similar to that of coal, kerosene and asphalt, and is made of organic matter accumulated by ancient plants and animals. The beds, always in shallow coastal waters, are rich in lower organic plants, scales, insects, and other deformed and difficult to identify animals. Its tissue is very fine, containing lime and sand inside, tough texture. It is a kind of rock with a delicate constitution, used to push sharps and other metal surfaces.

Industrial Applications
Whetstone sintered corundum (ruby) whetstone: A microcrystalline corundum product made by sintering at high temperatures, having a compact and delicate structure and high hardness and strength.