The 32 crystal classes - Crystallography |Geologypage

Crystallographic system and 32 crystal classes

Crystallographic System	S.I .No. of Class	Class Name	Herman Mauginn Symbol	General Form	Mineral
Triclinic	1	Pinacoidal (holohedral)	ī	Pinacoid	Plagioclase feldspar, axinite and kyanite
	2	Pedial or asymmetric (hemihedral)	1	Pedion	Calcium thio-sulphate
Monoclinic	3	Monoclinic prismatic (holohedral)	2/m	Monoclinic Prism	Micas, Gypsum, chlorite,orthoclase and many members of pyroxene, amphibole and epidote groups
	4	Monoclinic domatic (hemihedral)	m	Dome	Clinohedrite
	5	: Monoclinic sphenoidal (hemimorphic)	2	Sphenoid	Tartaric acid, Pickeringite
Orthorhombic	6	Orthorhombic dipyramidal (holosymmetric) class	2/m 2/m 2/m	Orthorhombic dipyramid	Anglesite, barite, sulphur, stibnite, forsterite. Brookite, cordierite, andalausite and sillimanite
	7	Orthorhombic pyramidal (hemimorphic)	mm2 (or 2mm)	Orthorhombic pyramid	Hemimorphite, Calamine, Struvite
	8	Rhombic-disphenoidal	222	Rhombic di-sphenoid	Epsomite
Tetragonal System	9	Ditetragonal di-pyramidal	4/m 4/m 4/m	Ditetragonal-dipyramid	Zircon, Vesuvianite, Rutile, Cassiterite
	10	Ditetragonal pyramidal	4mm	Ditetragonal pyramid	Iodosuccinimide, Diaboleite
	11	Tetragonal-trapezohedral	422	Tetragonal Trapezohedron	Nickel-sulphate, Phosgenite
	12	Tetragonal-scalenohedral	-42m	Tetragonal scalenohedron	Chalcopyrite
	13	Tetragonal-dipyramidal class	4/m	Tetragonal Dipyramid	Sceelite,Scapolite
	14	Tetragonal-disphenoidal	-4	Tetragonal Disphenoid	Cahnite
	15	Tetragonal-pyramidal	4	Tetragonal Pyramid	Wulfenite
Hexagonal system	16	Dihexagonal dipyramidal	6/m 2/m 2/m	Dihexagonal dipyramid	Beryl
	17	Ditrigonal dipyramidal	-6m2	Ditrigonal dipyramid	Bentonite
	18	Dihexagonal pyramidal class or Dihexagonal hemimorphic	6mm	Dihexagonal pyramid	Zincite
	19	Hexagonal trapezohedral	622	Hexagonal trapezohedron	β-quartz, Kalisillite
	20	Hexagonal dipyramidal class	6/m	Hexagonal dipyramid	Apatite
	21	Trigonal dipyramidal	-6	Trigonal dipyramid	Disilver ortho-phosphate
	22	Hexagonal pyramidal	6	Hexagonal pyramid	Nephelite
Trigonal (Rhombohedral division of the Hexagonal system)	23	Trigonal holosymmetric or Ditrigonal scalenohedral	-32/m (=3m)	Ditrigonal scalenohedron	Calcite, Corundum and hematite.
	24	Ditrigonal pyramidal or Ditrigonal hemimorphic	3m	Ditrigonal pyramid	Tourmaline
	25	Trigonal trapezohedral	32	Trigonal trapezohedron	α-quartz
	26	Rhombohedral	-3	Rhombohedron	Phenacite, Dolomite
	27	Trigonal pyramidal or Trigonal hemimorphic	3	Trigonal pyramid	Sodium Periodate, Gratonite
Isometric	28	Hexoctahedral or Holohedral	4/m -3 2/m (m3m)	Hexoctahedron	Galena, Halite, Fluorite, Spinel, Garnet
	29	Hextertahedral	-43m	Hextetrahedron	Tetrahedrite, Sphalerite
	30	Pentagon trisoctahedral or Gyroidal	432	Gyroid	Cuprite
	31	Diploidal or Didodecahedral	2/m -3	Diploid	Pyrite
	32	Tetroidal or Pentagon tristetrahedral	23	Pentagon tristetrahedron	Ullmanite Cobaltite

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