Quiz 4
1. Hypabysal igneous rocks are those formed ___________________ ?
A. deep below the surfaceB. on the surfaceC. at shallow depth below the surfaceD. by extrusion into water
2. Mafic igneous rocks contain lots of ___________________ ?
A. iron & magnesium bearing mineralsB. quartz and feldsparC. topaz and micaD. diamonds
3. An igneous rock which is coarse-grained, has a medium tone (color), and contains less than 10% quartz would be called a ___________________ ?
A. graniteB. gabbroC. dioriteD. andesite
4. According to Streckheisen's classification, a plutonic rock containing less than 5% quartz and between 35% and 65% alkali feldspar is called a ________________________ ?
A. granodioriteB. tonaliteC. graniteD. monzonite
5. Coarse-grained igneous rocks with clearly visible crystals are called _______________ ?
A. phaneriticB. aphaniticC. hyalophiticD. apophyses
6. The process of changing a melt composition by progressive removal of crystals of different minerals is called ____________________ ?
A. fractional crystallizationB. isostasyC. gravitational attractionD. osmosis
7. Which of the following is not a common rock-forming mineral ?
A. quartzB. topazC. feldsparD. mica
8. Chromite deposits are thought to form by ____________________ ?
A. volcanic eruptionB. settling of chromite grains to the bottom of the magma chamberC. alteration of iron oxideD. reaction of pyroxene with mica
9. Pegmatites can form ore deposits which are mined for ______________________ ?
A. goldB. ironC. zincD. rare elements in accessory minerals
10. Which of these minerals are formed exclusively in kimberlite ultramafic, pipe-shaped intrusions ?
A. corundumB. diamondsC. hornblendeD. biotite