Tuesday, May 16, 2017

Crystals That Show Twinning

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. 

aragonite (40 mm length)
gypsum (37 mm length)

pyrite cubes (47 mm length)
quartz (47 mm length)
staurolite (18 mm length)
pseudomorph of staurolite (40 mm)

pseudomorph of staurolite (40 mm length)

pseudomorphs are formed
when a mineral is replaced
by a foreign substance

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