Metamorphic rocks

Question 1

Gneiss

Answer 1

foliated rock, high grade of metamorphism, alternating bands of felsic and mafic minerals, Protolith is schist, granite and rhyolite

Question 2

Greenstone

Answer 2

Non foliated rock, Protolith is basalt, gabbro, peridotite. Tough dark altered mafic rock that was once solid deep sea lava. Green to black, fine grained massive texture. Harder than glass. High pressure and warm fluids, subduction zones.

Question 3

Marble

Answer 3

Non foliated rock, coarse grained, formed from carbonate rocks, Regional or contact metamorphism
Stretched pebble Conglomerate – Protolith: conglomerate. Shear stress from tectonic forces. Stretches/flattens grains

Question 4

Phyllite

Answer 4

foliated rock, moderate grade, minerals are white mica some chlorite, feldspar may begin to form. Protolith is shale and slate

Question 5

Schist

Answer 5

foliated rock. Grade is medium. Minerals: chlorite is now gone, garnet may form. Special: Parallel layers, minerals grow much larger such as mica. Protolith: Basalt, peridotite -> greenschist: shale, slated rhyolite (rare) -> schist

Question 6

Slate

Answer 6

Foliated rock. Grade is low. Minerals are fine but not visible, clays, mica, chlorite, quartz. Splits into think sheets, harder than shale. Protolith (parent rock) is shale, mudstone