Ilvaite
Ilvaite is a sorosilicate mineral recognized among collectors for its crystal form and distribution, with known Chinese sources.
Ilvaite is a black calcium-iron silicate of iron skarns, famous among collectors for the lustrous, sharply striated prismatic crystals of the Huanggang Mine in Inner Mongolia — now the world’s definitive source.
About Ilvaiteextended article
Ilvaite is a calcium iron sorosilicate that forms in iron skarns and metasomatic deposits. Its opaque black crystals — with a near-metallic to resinous lustre and a sharp, deeply striated prismatic habit — have made it one of the most sought-after skarn minerals, and China is now its definitive source.
The Huanggang standard
Since the 2000s the Huanggang iron-tin skarn in Hexigten Banner, Inner Mongolia, has produced ilvaite of a quality unmatched anywhere: jet-black, lustrous, deeply striated prisms to 10 cm and beyond, frequently perched on contrasting quartz, calcite, or fluorite and associated with green hedenbergite and andradite garnet. This material reset the global benchmark for the species.
What collectors look for
Crystal sharpness, length, and the silvery-black lustre that catches the light along the striations are the value drivers, together with an undamaged termination and an aesthetic association — hedenbergite sprays, druzy quartz, or fluorite. Combination pieces are especially prized.
Care
Ilvaite is stable but, like many iron-rich species, is best kept dry and out of prolonged strong light; avoid acids when cleaning. See the Huanggang Mine page for the locality in detail.
About Ilvaite
Ilvaite belongs to the sorosilicate class in the ilvaite group and has the chemical formula CaFe2+2Fe3+(Si2O7)O(OH). It crystallizes in the orthorhombic system and holds a steady position among sorosilicate species.
Identification & care
Specimens usually show prismatic striated crystals, often elongated; bladed; massive; columnar. Its color is typically black, brownish black and iron black. The luster is submetallic to vitreous, the streak is black to greenish black, and specimens are typically opaque. The cleavage is distinct {001} and {010}. The fracture is uneven to conchoidal, which aids identification.
Collector context
Collector notes
Among collectors of crystallized species, Ilvaite is a recognized reference. Ilvaite is widely represented across Chinese provinces, including Yunnan, Inner Mongolia, Tibet, Hubei.
Frequently asked questions
What is Ilvaite?
Ilvaite is a sorosilicate mineral recognized among collectors for its crystal form and distribution, with known Chinese sources.
What is the chemical formula of Ilvaite?
The chemical formula of Ilvaite is CaFe2+2Fe3+(Si2O7)O(OH).
What crystal system does Ilvaite belong to?
Ilvaite crystallises in the Orthorhombic crystal system.
Where is Ilvaite found?
Notable localities for Ilvaite include Huanggang Mine.
References & databases
Mindat.org is the world’s largest open mineralogy database. Our descriptions are written independently and fact-checked.