Topic summary
Pyroxenes
Extracted from the Wikipedia article Pyroxene.
Structure
Pyroxenes are the most common single-chain silicate minerals (the only other important group of single-chain silicates, the pyroxenoids, are much less common.) Their structure consists of parallel chains of negatively-charged silica tetrahedra bonded together by metal cations. In other words, each silicon ion in a pyroxene crystal is surrounded by four oxygen ions forming a tetrahedron around the relatively small silicon ion. Each silicon ion shares two oxygen ions with neighboring silicon ions in the chain.