Spinel
Spinel is an oxide mineral valued for its hardness and gem potential, with several world-class Chinese localities.
About Spinel
Spinel is an oxide mineral in the spinel group and has the chemical formula MgAl2O4. It crystallizes in the isometric system and is one of the most visually varied minerals in the collector market. Its combination of structural character and global distribution make it a recognized species in both systematic and aesthetic collections.
Identification & care
Spinel typically forms octahedral crystals (classic habit), sometimes twinned (spinel twins/macles); massive, granular. Its color range is broad, including colorless, white, red (ruby spinel), pink, orange, blue, green, purple, brown, black, and virtually every color possible. The luster is vitreous, the streak is white, and specimens range from transparent to opaque. The cleavage is imperfect on {111}. The fracture is conchoidal, uneven, which aids identification.
Collector context
How it forms
Spinel forms in mafic/ultramafic igneous rocks and their metamorphic derivatives; marble and calc-silicate skarns; alluvial gem gravels. It is commonly found in association with corundum (ruby/sapphire), pyrope garnet, diopside, calcite, dolomite, phlogopite.
Classic Chinese localities
Documented Chinese occurrences are recorded at Shangbao Mine, Xianghualing Sn-polymetallic ore field and Yaogangxian W-Sn ore field, among others.
Why collectors care
Spinel occupies a rare position: it matters equally to specimen collectors and to the gem trade. Crisp natural crystals with saturated color and good clarity command premium pricing and are among the highest-prestige targets in any systematic collection.
What affects value
Value in Spinel is assessed, in typical order of weight, against: (1) locality provenance; (2) crystal size; (3) transparency and internal clarity; (4) color intensity and saturation; (5) crystal form and termination sharpness; (6) matrix and associated-species aesthetics; (7) gem-cutting potential. Verified locality documentation and cutting potential further elevate collector demand.
Naming history
The name Spinel has a specific etymological and historical context — see Mindat's reference entry for provenance details. We have retained naming data at the record level; published prose is paraphrased from factual fields rather than copied from source.