Fornacite

CuPb₂(CrO₄)(AsO₄)(OH)

Grandfathered

Chemical formula (IMA record): CuPb₂(CrO₄)(AsO₄)(OH)
Recognition status: Grandfathered
Original-description year in master list: 1915
First-discovery country (IMA): Republic of the Congo
Crystal system: Not supplied in the IMA master list
Mohs hardness: Not supplied in the IMA master list
Measured density: Not supplied in the IMA master list
Historical discoverer: Not supplied in the IMA master list

How it occurs in nature

This species has a documented chemistry and recognition record in the IMA catalog. The master list does not describe its formation environment. Consult the cited mineral-description studies below for species-specific occurrence and geological context; these cannot be inferred reliably from the formula alone.

Discovery & scientific record

The country refers to the master list’s first-discovery country, using modern borders. It is not a list of all deposits. A question mark is retained when the source is uncertain; a special-procedure date can refer to redefinition rather than discovery.

Original reference: Bulletin de la Société Française de Minéralogie 38 (1915), 198

Additional reference: Doklady Earth Sciences 456 (2014), 520

IMA-CNMNC master list · page 77 ↗

RRUFF · further mineral research ↗ · Handbook of Mineralogy ↗

Catalog coverage and profile depth are different: every species in the cited IMA edition is indexed, but this edition does not provide every physical property or a full discovery narrative. The archive leaves those gaps explicit. Formulae and references are adapted from the IMA list under CC BY-SA 3.0; consult the original page for authoritative typography.

Reference snapshot: September 2026. Source dates and uncertainties are retained in the record.