Silicate Minerals (I)

Question 1

Two broad classification of minerals.

Answer 1

Silicates and Non-silicates

Question 2

When pertaining to Minerals Abundances, what is the percent abundance of Plagioclase Feldspars?

Answer 2

39%

Question 3

When pertaining to Mineral Abundances, what is the percent abundance of Potassium Feldspar?

Answer 3

12%

Question 4

When pertaining to MIneral Abundances, what is the percent abundance of Quartz?

Answer 4

12%

Question 5

When pertaining to Mineral Abundances, what is the percent abundance of Pyroxenes?

Answer 5

11%

Question 6

When pertaining to Mineral Abundances, what is the percent abundance of Amphiboles?

Answer 6

5%

Question 7

When pertaining to Mineral Abudances, what is the percent abundance of Micas?

Answer 7

5%

Question 8

When pertaining to Mineral Abudances, what is the percent abundance of Clays?

Answer 8

5%

Question 9

When pertaining to Mineral Abudances, what is the percent abundance of all the Other Silicate Minerals?

Answer 9

3%

Question 10

When pertaining to Mineral Abudances, what is the percent abundance of Non-silicates?

Answer 10

8%

Question 11

Two bases for clasification of minerals.

Answer 11

Crystal Structure and Chemical Composition

Question 12

Largest Group of Minerals.

Compounds Containing Silicon and Oxygen.

Building Block: Silicon Tetrahedron (SiO4)^-4.

Answer 12

Silicates

Question 13

Determine the kind of Silicate:

Independent Silica Tetrahedron

Densely packed tetrahedra and bounded to one another via ionic bonds with interstitial cations.

Crystal habits are equidimensional and lack pronounced cleavage.

*Mostly ferromagnesian minerals

Answer 13

Nesosilicates

Question 14

A nesosilicate mineral subgroup characterized by;

High relief, Relatively Strong Birefringence, Fair Cleavage, and Parallel Extinction

Can be confused with Pyroxenes, and alters to Serpentine Minerals

Common in Subsilicic, Mafic, Ultramafic, Metamorphic Limestones, and Contact Metamorphic Rocks

Rare in Pegmatites, Obsidians, and Ores

Answer 14

Olivine Group

Question 15

Iron-rich member of the Olivine group.

Answer 15

Fayalite

Question 16

Magnesium-rich member of the Olivine group.

Answer 16

Forsterite

Question 17

What is the 2V angle of forsterite?

Answer 17

85 to 90 Degrees

Question 18

What is the 2V angle of Fayalite?

Answer 18

47 to 54 Degrees

Question 19

True or False:

Fayalite is the more common member of the Olivine Group.

Answer 19

False, Forsterite is more common, thus Fayalite is rarer.

Question 20

A group under the nesosilicate minerals, which include the Aluminium and Calcium Silicates.

Answer 20

Garnet Group

Question 21

Series of minerals under the Garnet group characterized by being the Aluminium Silicates.

Answer 21

Pyralspite Series (Pyrope, Almandine, Spessartine)

Question 22

Series of minerals under the Garnet group characterized by being the Calcium Silicates.

Answer 22

Ugrandite Series (Uvarovite, Grossularite, Andradite)

Question 23

Which garnet series has the higher index of refraction, Pyralspite Series or Ugrandite Series?

Answer 23

Ugrandite Series

Question 24

Three Members of the Aluminosilicate Polymorphs.

Answer 24

Andalusite, Sillimanite, and Kyanite

Question 25

Paired (“sister”) Silica Tetrahedra. Isolated Pyrosilicate Anions (Si2O6^−7). Consisting of double tetrahedra with a shared oxygen vertex.

Answer 25

Sorosilicates

Question 26

Minerals under the Sorosilicate Category

Answer 26

Epidote Supergroup and Lawsonite Group

Question 27

Ring Silica Tetrahedra 3-, 4-, 6-, 8-, 9-, or 12- Membered Rings of Si^4+ Tetrahedra Strongly linked bonds yield relatively dense and hard minerals.

Answer 27

Cyclosilicates

Question 28

Members of the Cyclosilicate Category

Answer 28

Tourmaline Group, Beryl Group, Cordierite

Question 29

Chained Silica Tetrahedra Have Interlocking Chains of Silicate Tetrahedra with SiO3. Pyroxenes

Answer 29

Single-chain Inosilicates

Question 30

Which member of the Inosilicate category: Good to fair cleavages at ~93° Occasional simple twins Biaxial with large 2V angles Some are pleochroic large range of extinction angles for the Monoclinic members 6-50°) Most common members: augite, pigeonite Occurs in subsilicic igneous rocks, metamorphic rocks, meteorites

Answer 30

Pyroxene Group

Question 31

Single-chain Inosilicate, short and stubby.

Answer 31

Pyroxenes

Question 32

Two classifications of Pyroxenes.

Answer 32

Orthopyroxenes and Clinopyroxenes

Question 33

Members of Orthopyroxenes include?

Answer 33

Estatite, Bronzite, Hypersthene, Ferrosiltite

Question 34

Members of the Clinopyroxene group include?

Answer 34

Augite, Diopside, Pigeonite, Hedenbergite, Aegirine, Jadeite, Spodumene, Omphacite, Aegirine-Augite

Question 35

Double-chain Inosilicates, long and slender.

Answer 35

Amphiboles

Question 36

Two classifications of amphiboles.

Answer 36

Clinoamphiboles and Orthoamphiboles

Question 37

Chained Silicon Tetrahedra Has interlocking Chains of Silicate Tetrahedra with Si4O11 Amphiboles

Answer 37

Double-chain Inosilicates

Question 38

Pseudohexagonal cross-sections Perfect cleavage at 56-124° Simple twins common Common species: hornblende, basaltic hornblende: lamprobolite Colored and often pleochroic

Answer 38

Amphibole Group

Question 39

Members of the Orthoamphibole group.

Answer 39

Anthophyllite

Question 40

Members of the Clinoamphibole group.

Answer 40

Hornblende, Riebeckite, Cummingtonite, Crunerite, Tremolite-Actinolite, Nephrite, Lamprobolite, Glaucophane

Question 41

Which kind of Amphibole minerals are more common?

Answer 41

Clinoamphiboles

Question 42

Silicate minerals that are also called as chain silicates, that can be single-chain or double-chain, commonly monoclinic and orthorhombic.

Answer 42

Inosilicates

Question 43

How to easily identify Pyroxenes or Amphiboles as Monoclinic or Orthorhombic?

Answer 43

Extinction Type/Angle: Monoclinic: Inclined Extinction Orthorhombic: Parallel Extinction

Question 44

Garnet has ______ cleavage directions.

Answer 44

Zero

Question 45

Olivine has _______ relief.

Answer 45

High

Question 46

True or False: Amphiboles have inclined extinction.

Answer 46

Partially true. Generally, it exhibits inclined extinction, but not all the time. Orthoamphiboles are much rarer than Clinoamphiboles; Clinoamphiboles exhibit Inclined Extinction.

Question 47

Ratio and Cation of Nesosilicates

Answer 47

1:4, (SiO4)^-4

Question 48

Ratio and Cation of Sorosilicates

Answer 48

2:7 , (Si2O7)^-6

Question 49

Ratio and Cation of Cyclosilicates

Answer 49

1:3, (Si6O18)^-12

Question 50

Ratio and Cation of Single-chain Inosilicates

Answer 50

1:3, (Si2O6)^-4

Question 51

Ratio and Cation of Double Chain Inosilicates

Answer 51

4:11, (Si4O11)^-6

Question 52

Ratio and Cation of Phyllosilicates

Answer 52

2:5, (Si2O5)^-2

Question 53

Ratio and Cation of Tectosilicates

Answer 53

1:2, SiO2