Granites, for example, have more than 10% quartz and abundant potassium feldspar.Other plutonic rocks have less quartz and potassium, and different ratios of calcium and sodium feldspar minerals.
Discoloration haloes in younger rocks tend to be smaller and less intense than in older rocks, indicating that the zone of crystal damage increases with time.
From these observations early attempts were made to use the dimensions of haloes as an age dating technique.
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The crystals develop an interlocking texture with some of the trace minerals becoming completely surrounded by later forming crystals.
Volcanic rocks, because they are able to cool and crystalize rapidly, have a very fine-grained texture; the individual mineral grains are too small to see easily with the naked eye.
Note that the halo has the highest intensity of discoloration near the source, gradually fading with distance in the host mineral to a "fuzzy" edge.
Radiation damage haloes around mineral inclusions are well known from the geological literature.
When burial pressures and temperatures get too great, the rocks melt completely, becoming new igneous rocks.