Pyroxene

Pyroxenes are a group of the rock-forming silicate minerals. They are comprised of single chains of silica tetrahedra and have the general formula XY(Si,Al)₂O₆. X represents calcium, sodium, iron⁺² and magnesium and more rarely zinc, manganese and lithium. Y represents ions of smaller size, such as chromium, aluminium, iron⁺³, magnesium, manganese, scandium, titanium, vanadium and even iron⁺². Although aluminium commonly substitutes for silicon in other silicates, it usually doesn't substitute for silicon in a pyroxene.

The name pyroxene comes from the Greek words for fire and stranger. It was named thusly due to their presence in volcanic lavas, where they are sometimes seen as crystals embedded in volcanic glass; it was assumed that were impurities in the glass, hence the name "fire strangers". However, they are simply early forming minerals that crystallized before the lava erupted.

The mantle of Earth is composed mainly of olivine and pyroxene.

Some pyroxenes:

• Clinopyroxenes (monoclinic)
  • Aegirine (Sodium Iron Silicate)
  • Augite (Calcium Sodium Magnesium Iron Aluminum Silicate)
  • Clinoenstatite (Magnesium Silicate)
  • Diopside (Calcium Magnesium Silicate, CaMgSi₂O₆)
  • Esseneite (Calcium Iron Aluminum Silicate)
  • Hedenbergite (Calcium Iron Silicate)
  • Hypersthene (Magnesium Iron Silicate)
  • Jadeite (Sodium Aluminum Silicate)
  • Jervisite (Sodium Calcium Iron Scandium Magnesium Silicate)
  • Johannsenite (Calcium Manganese Silicate)
  • Kanoite (Manganese Magnesium Silicate)
  • Kosmochlor (Sodium Chromium Silicate)
  • Namansilite (Sodium Manganese Silicate)
  • Natalyite (Sodium Vanadium Chromium Silicate)
  • Omphacite (Calcium Sodium Magnesium Iron Aluminum Silicate)
  • Petedunnite (Calcium Zinc Manganese Iron Magnesium Silicate)
  • Pigeonite (Calcium Magnesium Iron Silicate)
  • Spodumene (Lithium Aluminum Silicate)
• Orthopyroxenes (Orthorhombic)
  • Donpeacorite (Manganese Magnesium Silicate)
  • Enstatite (Magnesium Silicate)
  • Ferrosilite (Iron Magnesium Silicate)
  • Nchwaningite (Hydrated Manganese Silicate)

• Schefferite[?], Ca(Mg,Fe,Mn)Si₂O₆
• Zinc schefferite[?], Ca(Mg,Mn,Zn)Si₂O₆
• Jeffersonite[?], Ca(Mg,Fe,Mn,Zn)Si₂O₆
• Leucaugite[?], Ca(Mg,Fe,Al)(Al,Si)₂O

External links

• [1] (http://mineral.galleries.com/minerals/silicate/pyroxene.htm)