Pyroxenes

Monoclinic

Ca - Mg - Fe²⁺

Augite (Ca,Mg,Fe²⁺,Fe³⁺,Al,Ti)₂[(Si,Al)₂O₆]

	Colour: light pink, colourless Pleochroism: non to weakly pleochroic Habit: stubby prisms, commonly cross sections are 8 sided Relief: positive Cleavage, fracture: in horizontal section - good, single cleavage, in cross sections - good, double cleavage at 87º
	Isotropic or anisotropic: anisotropic Extinction: inclined Interference colours: 2nd order Distinguished features: sector zoning (as seen on the left)

Diallage

	Perfect, one direction (100) cleavage version of augite. Particularly rich in magnesium.

Alkaline

Aegirine NaFe³⁺[Si₂O₆]

	Colour: green, yellow Pleochroism: pleochroic Habit: stubby prisms, commonly cross sections are 8 sided Relief: positive Cleavage, fracture: in horizontal section - good, single cleavage, in cross sections - good, double cleavage at 87º
	Isotropic or anisotropic: anisotropic Extinction: inclined Interference colours: 2nd/3rd order