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Any ideas about the origin of this formation?

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 I got my hands on a beautiful piece of crystal. No name attached to it and it’s structure is different than usual quarts crystals and it’s harder than calcite and fluorite. Very shiny and bright. Rough and untreated. The lower rock is a rough piece of regular quartz crystal and the upper rock on the picture is the rock I’m describing here. 

asked Oct 13, 2018 by Lemurian (950 points)

2 Answers

0 votes
Corrundum, maybe? It is known to have those ripple-like folds within it, a sort of strained prismatic structure. It also could be gypsum, but gypsum is soft and if it is harder than calcite, that is unlikely. Could you post a back lit photo?
answered Oct 15, 2018 by linkisnotzelda (5,390 points)
The formation looks of metamorphic orgin.
0 votes
The lower picture does look like quartz - its got the right form and luster.

The top one, however, looks very similar to the other identifiable material you described previously. I doubt its Corundum. Its luster and striations, and high hardness your described earlier, would likely make it topaz or phenakite.
answered Oct 18, 2018 by hershel (52,800 points)

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