A2 Igneous Processes

Question 1

Reaction rim

Answer 1

one mineral surrounding another, as a result of a reaction between the inner mineral with the melt, to form the outer mineral.

Question 2

Liquidus

Answer 2

a phase boundary showing the temperature where the last solid particle melts.

Question 3

Solidus

Answer 3

a phase boundary showing the temperature when a rock first begins to melt when heated.

Question 4

Platinum group elements (PGE)

Answer 4

comprise: platinum (Pt), palladium (Pd), iridium (Ir), osmium (Os), rhodium (Rd) and ruthenium (Ru).

Question 5

Chalcophile elements

Answer 5

combine more readily with sulfur than with oxygen.

Question 6

Siderophile elements

Answer 6

dissolve in iron, either as solid solutions or in the liquid state. They form bonds with carbon or sulfur but not with oxygen.

Question 7

Cumulate igneous rocks

Answer 7

are formed by the accumulation of crystals due to gravity settling and are typical of layered intrusions.