Stone

** What are stones? **  In geology, rock or stone is a naturally occurring solid aggregate of minerals and/or mineraloids. The Earth's outer solid layer, the lithosphere, is made of rock. In general, rocks are of three types, namely igneous, sedimentary, and metamorphic. The scientific study of rocks is called petrology, and petrology is an essential component of geology. ** How many kinds of stone do you know? **
 * Stone **

Igneous
**Andesite** - an intermediate volcanic rock. **Anorthosite** - an igneous ultramafic rock composed predominantly of plagioclase. **Aplite** - a very fine grained intrusive igneous rock. **Basalt** - a volcanic rock of mafic composition. **Kimberlite** - a rare ultramafic, ultrapotassic volcanic rock and a source of diamonds.