<Tr> <Td_colspan="2"> <Ul> <Li> view </Li> <Li> talk </Li> <Li> </Li> </Ul> references in Wikidata </Td> </Tr> <Ul> <Li> view </Li> <Li> talk </Li> <Li> </Li> </Ul> <P> Boron is a chemical element with symbol B and atomic number 5 . Produced entirely by cosmic ray spallation and supernovae and not by stellar nucleosynthesis, it is a low - abundance element in the Solar system and in the Earth's crust . Boron is concentrated on Earth by the water - solubility of its more common naturally occurring compounds, the borate minerals . These are mined industrially as evaporites, such as borax and kernite . The largest known boron deposits are in Turkey, the largest producer of boron minerals . </P> <P> Elemental boron is a metalloid that is found in small amounts in meteoroids but chemically uncombined boron is not otherwise found naturally on Earth . Industrially, very pure boron is produced with difficulty because of refractory contamination by carbon or other elements . Several allotropes of boron exist: amorphous boron is a brown powder; crystalline boron is silvery to black, extremely hard (about 9.5 on the Mohs scale), and a poor electrical conductor at room temperature . The primary use of elemental boron is as boron filaments with applications similar to carbon fibers in some high - strength materials . </P>

Where is the element boron found in nature