Mogok Township, Pyin-Oo-Lwin District, Mandalay Region, Myanmar

MgAl₂O₄

Crystal System:cubic
Colour: black, blue, red, violet , green, brown or pink
Lustre: vitreous
Habitus: commonly in octahedral crystals. Also in granular to massive aggregates
Hardness: 7½ - 8 
Fracture: irregular/uneven, splintery, conchoidal
Cleavage: none observed
Density:  3.578 g/cm³ 
Origin and geological occurrence: it is a common mineral in metamorphic Al-Mg-bearing dolostone. Furthermore, it occurs in granulite or high-pressure basic magmatic rocks. Also, it can be found in alluvial or sea placers due its hardness and strength.

www.mindat.org
Smorf link

Samples:

4.15 Spinel Cluster of octahedral crystals #oxides