Mineral mix

Question 1

Clinopyroxene

Answer 1

pyroxene that contains Ca apart from Fe and Mg and is monoclinic

Question 2

Orthopyroxene

Answer 2

pyroxene with orthorhombic crystal system and Fe-Mg solid-solution

Question 3

Serpentine

Answer 3

Forms when olivine is hydrated. Contains Mg, but not iron from the olivine. Iron goes into a new mineral (magnetite)

Question 4

coupled substitution

Answer 4

For example Na+Si exchanges with Ca+Al in plagioclase

Question 5

The Al2SiO5 polymorphs

Answer 5

Andalusite, Sillimanite, Kyanite

Question 6

3 Ring-silicates

Answer 6

Tourmaline, beryl, cordierite

Question 7

ultramafic

Answer 7

rock or melt that contains around 40-45wt% SiO2 (example: mantle rocks)

Question 8

The blue amphibole

Answer 8

Glaucophane (occurs in blueschists, high P- low T)

Question 9

typical twinning in plagioclase

Answer 9

polysynthetic

Question 10

2 examples of minerals in the group of halogenides

Answer 10

halite, fluorite

Question 11

2 examples of sulphates

Answer 11

Gypsum, baryte

Question 12

Metapelite

Answer 12

metamorphosed shale

Question 13

Mg-rich garnet

Answer 13

Pyrope occurrence in mantle rock (garnet-peridotite) or eclogite

Question 14

Ca-rich garnet

Answer 14

Grossular occurrence in metamcarbonates, skarn

Question 15

Fe-rich garnet

Answer 15

Almandine occurrence in metamorphosed shale

Question 16

Chemistry of plagioclase

Answer 16

Solid-solution between Na and Ca

Question 17

Chemistry of alkali feldspar

Answer 17

Solid-solution between Na and K (only at high T)

Question 18

Perthite

Answer 18

Alkali-feldspar that unmixed during slow cooling into Na and K-rich domains

Question 19

Sanidine

Answer 19

High-T alkali-feldspar

Question 20

fractional crystallisation

Answer 20

minerals that form in a melt (magma) are ‘removed’ and are not in equilibrium with the surrounding melt