In my March 31, 2017 post concerning a distinctive granite, I showed an orthoclase crystal with twinning, which occurs when two separate crystals of the same substance share some of the same crystal lattice. Instead of a normal single crystal, the crystalline structure appears doubled.
In this new post, I show some other common examples from my personal collection of twinned crystals. They are aragonite, pyrite, gypsum, quartz, and staurolite.
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| aragonite (40 mm length) |
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| gypsum (37 mm length) |
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| pyrite cubes (47 mm length) |
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| quartz (47 mm length) |
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| staurolite (18 mm length) |
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pseudomorph of staurolite (40 mm)
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| pseudomorph of staurolite (40 mm length) |
pseudomorphs are formed
when a mineral is replaced
by a foreign substance
