Cubic (Isometric)
4/m -3 2/m (Oh)
Three equal axes at 90 degrees (a = b = c, alpha = beta = gamma = 90)
The cubic or isometric crystal system features three mutually perpendicular axes of equal length. Minerals in this system have the highest degree of symmetry. Common crystal forms include the cube, octahedron, and dodecahedron. Examples include diamond, garnet, pyrite, halite, and fluorite.
The cubic or isometric crystal system is the most symmetrical of all seven crystal systems, with three axes of equal length intersecting at 90-degree angles. This high symmetry produces some of the most recognizable crystal shapes in mineralogy: perfect cubes, octahedra, and dodecahedra. Approximately 12% of known mineral species crystallize in the cubic system, including many of the world's most economically important and visually stunning minerals.
Symmetry
Cubic symmetry means a crystal looks identical when rotated 90° around any of its three axes (a₁ = a₂ = a₃, all at 90°). This produces 36 symmetry elements — the maximum possible for any crystal system. The five cubic crystal classes range from the highly symmetric hexoctahedral class (like diamond and garnet) to the less symmetric tetartoidal class (like ullmannite). Crystals in this system can form cubes {100}, octahedra {111}, rhombic dodecahedra {110}, and complex combinations. Pyrite often forms perfect cubes with striated faces, while garnets characteristically form dodecahedra.
Minerales notables
Diamond — the hardest known natural material (Mohs 10) — crystallizes in the cubic system, as does its industrial counterpart spinel. Halite (rock salt) forms near-perfect cubes, making it a classic teaching specimen. Garnets are perhaps the most diverse cubic mineral group, with species like almandine, pyrope, and grossular spanning a range of compositions and colors. Fluorite is famous for its octahedral cleavage and wide color range including the deep purple of Derbyshire 'Blue John.' Galena (lead sulfide) forms distinctive metallic cubes and is the primary ore of lead. Gold and silver also crystallize in the cubic system, though they rarely form visible crystals.
Minerales (13)
Garnet (Almandine)
Fe3Al2(SiO4)3
09 Silicates
Halite
NaCl
03 Halides
Gold
Au
01 Native Elements
Silver
Ag
01 Native Elements
Copper
Cu
01 Native Elements
Sphalerite
ZnS
02 Sulfides and Sulfosalts
Spinel
MgAl2O4
04 Oxides and Hydroxides
Sodalite
Na4Al3Si3O12Cl
09 Silicates
Diamond
C
01 Native Elements
Fluorite
CaF2
03 Halides
Pyrite
FeS2
02 Sulfides and Sulfosalts
Magnetite
Fe3O4
04 Oxides and Hydroxides
Galena
PbS
02 Sulfides and Sulfosalts