Answer the following about rutile, or titanium dioxide, for 10 points each.
[10m] Rutile exhibits one of the highest magnitudes of this optical phenomenon for any crystal. This phenomenon, in which materials exhibit two different values of index of refraction, was first observed in calcite crystals.
ANSWER: birefringence [or birefringent]
[10e] Nanoparticles of rutile strongly absorb this radiation, leading it to be used in many sunscreens. Impurities in minerals like calcite and fluorite cause them to glow when exposed to this kind of radiation.
ANSWER: ultraviolet [or UV; accept UV-A or UV-B or UV-C; prompt on blacklight by asking “what type of radiation is emitted by a blacklight?”]
[10h] Rutile is an accessory mineral of this metamorphic rock that consists of garnet and omphacite. The presence of facies of this rock is indicative of ultra-high-pressure metamorphism.
ANSWER: eclogite
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