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So this is a rock I found on an island in Croatia, I thought that it was interesting because of the glittering parts on the rock itself. The rock does not react with magnets at all. I was hoping someone could help me identify it. Thanks in advance! enter image description here

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  • $\begingroup$ Please follow our guide on how to ask rock ID questions: earthscience.meta.stackexchange.com/q/124/725 and edit your question accordingly, so you can help us help you. Regardless of that, I'm pretty sure it's a mica schist, but need more information. $\endgroup$ – Gimelist Nov 8 '17 at 10:13
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The glittery part of the rock is mica. Mica is a class of minerals which belongs to sheet silicates. As you can see, crystals form sheets, which forms layers in the rock. Crystals tend to grow perpendicular to highest stress direction during deformation event, so that indicate metamorphism in the past. The presence of micas also indicate the composition of rock - it had to be aluminium rich before it was affected by heat and pressure. It is difficult to tell about the size of crystals but lack of other higher grade minerals or deformations suggests it's mica schist.

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