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The Six Crystal Families

by geofablab, published

The Six Crystal Families by geofablab Oct 21, 2013

Description

All minerals fall into one of six crystal classes based on the ordering of their component elements and polyatomic ions.

Isometric, a=b=c, alpha=beta=gamma=90 degrees

Tetragonal: a=bc, alpha, beta, and gamma equal 90 degrees

Orthorhombic: a, b, and c are unequal; alpha, beta, and gamma equal 90 degrees; a=20, b=30, c=40

Hexagonal: a=bc; alpha=beta=90 degrees, gamma=120 degrees;

Monoclinic, a, b, and c are unequal; alpha and gamma = 90 degrees, beta does not equal 90 degrees

Triclinic: a,b, and c are unequal; neither alpha, nor beta, nor gamma equal 90 degrees

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Peter...thanks for the suggestions. I have updated the models to remove the trigonal system as it is a subset of hexagonal family.
Hi geofablab,

I noticed that your monoclinic body has a beta angle of exactly 120 degrees, which makes it trigonal or hexagonal (in fact the two objects cc_trigonal.stl and cc_monoclinic.stl are identical). Of course beta=120 is allowed in the monoclinic system, but would it not be better to avoid a special case for educational purposes?

Cheers,

Peter

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Hi geofablab,

I noticed that your monoclinic body has a beta angle of exactly 120 degrees, which makes it trigonal or hexagonal (in fact the two objects cc_trigonal.stl and cc_monoclinic.stl are identical). Of course beta=120 is allowed in the monoclinic system, but would it not be better to avoid a special case for educational purposes?

Cheers,

Peter
Peter...thanks for the suggestions. I have updated the models to remove the trigonal system as it is a subset of hexagonal family.
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