Chapter: Civil : Engineering Geology : Mineralogy

Pyroxenes Group

It is important group of rock forming minerals.

PYROXENES GROUP

It is important group of rock forming minerals.

They are commonly occur in dark colours, igneous and metamorphic rocks They are rich in calcium, magnesium, iron, silicates

It show single chain structure of silicate

It is classified into orthopyroxene and clinopyroxene. It is based on internal atomic structure

ORTHOPYROX ENE: Enstatite

(MgSiO3)

Hyperthene [(Mg,Fe)SiO3]

CLINOPYROXENE:

Augite [(Ca, Na) (Mg, Fe, Al) (Al,

Si)2O6] Diopside [CaMgSi2O6]

Hedenbergite[CaFeSi2O6]

AUGITE:

CRYSTAL SYSTEM: Monoclinic

HABIT: Crystalline

CLEAVAGE: Good ( primastic cleavage)

FRACTURE: Conchoidal

COLOUR: shades of greyish green and black

LUSTRE: vitreous

HARDNESS: 5-6

SPECIFIC GRAVITY: medium

STREAK: white

OCCURRENCE: ferro magnesium mineral of igneous rock (dolerite)

USES: rock forming mineral

COMPOSITON: [(Ca, Na) (Mg, Fe, Al) (Al, Si)2O6]

TRANSPARENCY: Translucent/opaque

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Civil : Engineering Geology : Mineralogy : Pyroxenes Group |