(8) Silicates I Flashcards
Nesosilicates, Sorosilicates, Cyclosilicates, Inosilicates (23 cards)
2 Classification of Minerals
Silicates and Non-silicates
- largest group of minerals
- compounds containing silicon and oxygen
Silicate minerals
building block of silicate minerals
silicon tetrahedron (SiO3)^-4
- independent silica tetrahedron
- densely packed tetrahedra and bounded to one another via ionic bonds with interstitial cations
Nesosilicates
Best example of a Nesosilicate
olivine
- high relief
- relatively strong birefringence
- fair cleavage
- parallel extinction
Olivine Group
Two common minerals under Olivine Group
Fayalite and Forsterite
aluminum silicates
- pyrope
- rhodolite
- almandine
- spessartine
pyralspite series
calcium silicates
- uvarovite
- grossularite
- andradite
ugrandite series
The aluminosilicate polymorphs
andalusite
kyanite
sillimanite
Other nesosilicates to note
- Humite minerals
- Garnet group
- Sillimanite family
- Sphene
isolated pyrosilicate anions consisting of a double tetrahedral with a shared oxygen vertex
Sorosilicates
Best example of a sorosilicate
Epidote
- ring silica tetrahdra
- strongly linked bonds yield relatively dense and hard minerals
Cyclosilicates
Best example of a Cyclosilicate
Beryl
Other sorosilicates and cyclosilicates?
Sorosilicates:
Epidote group
Lawsonite
Cyclosilicates:
Beryl, tourmaline
- chained silica tetrahedra
- have interlocking chains if silicate tetrahedra with SiO3.
Inosilicates
- occasional simple twins
- biaxial with large 2V angles
- occurs in subsilicic igneous rocks, metamorphic rocks, meteorites
Pyroxene Group
Common Pyroxenes?
augite, pigeonite
Single chained inosilicates (minerals)
Orthopyroxene and Clinopyroxene
- simple twins common
- perfect cleavage at 56-124^o (degrees yan)
- colored and often pleochroic
Amphibole group
Common amphibole
Hornblende
Double-chain Inosilicate (minerals)
Orthoamphibole and Clinoamphibole
