Gypsum

Crystal system · Monoclinic

Gypsum is a sulfate mineral prized by collectors for its exceptional color range, with several world-class Chinese localities.

Popcorn gypsum with rounded nodular surface texture, Guizhou Province, China

Gypsum flower needle cluster specimen from China

Delicate botryoidal gypsum flower crystal from Guizhou, China

Gypsum flower formation on matrix from Guizhou, China

Popcorn gypsum specimen with nodular texture, Guizhou, China

Purple gypsum crystal cluster in floral formation from Guizhou, China

About Gypsumextended article

Gypsum is the Mohs-2 reference mineral and one of the most varied collector species. Its varieties span from the world's largest crystals (Naica selenite, 11+ meters) through the silky satin spar of stalactite caverns to the desert-rose rosettes of arid sand floors. Gypsum defines the second step of the Mohs hardness scale and dissolves slowly in water, producing some of the most fragile yet visually arresting display specimens.

Notable varieties

Selenite (transparent crystals; the Naica giants)
Satin spar (silky fibrous; cave deposits)
Alabaster (massive granular; carving stone)
Desert rose (rosette intergrowths in sand)
Swallowtail twins (V-shaped contact twins)

The Chinese angle

Chinese gypsum is industrially significant (Hunan, Hubei, Inner Mongolia) but specimen-grade material reaches the international market sporadically. Xinjiang produces some satin spar and selenite blades; Hunan stalactite caves yield occasional botryoidal satin spar. Most collector gypsum still flows from Mexico, Pakistan, Morocco, and the United States.

About Gypsum

Gypsum is classified as a sulfate mineral in the gypsum group and has the chemical formula CaSO₄·2H₂O. It crystallizes in the monoclinic 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

Crystals commonly develop as tabular, prismatic, lenticular; swallowtail twins; massive; fibrous; acicular; rosette (desert rose). Its color range is broad, including colorless, white, gray, yellowish, greenish, pinkish, and brownish. The luster is vitreous, silky, pearly, the streak is white, and specimens range from transparent to opaque. The cleavage is perfect on {010}, distinct on {100} and {011} — perfect in one direction. The fracture is fibrous, conchoidal, which aids identification.

Collector context

How it forms

In terms of geology, Gypsum forms in evaporite deposits; hydrothermal veins; secondary mineral in oxidized ore zones; cave environments. It is commonly found in association with calcite, halite, anhydrite, celestine, sulfur.

Classic Chinese localities

Documented Chinese occurrences are recorded at Jiama Cu-polymetallic deposit, Lingxiang Mine and Dachang ore field, among others.

Why collectors care

Gypsum is a frequently-sought species in serious collections because its habit is recognizable, its color often strong, and its best examples unmistakable even at a distance. Chinese material has driven much of the recent visual shift in the species — sharper crystals, deeper colors, cleaner matrix.

What affects value

Value in Gypsum is assessed, in typical order of weight, against: (1) locality provenance; (2) size relative to the species norm; (3) crystal form and termination sharpness; (4) color saturation and zoning; (5) transparency and internal clarity; (6) matrix quality and aesthetic balance; (7) condition (absence of damage, chips, or repair). Cleaning quality and verified locality documentation act as multipliers across the above.

Naming history

The name Gypsum 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.