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Formula: CuZnMn4+3O8
Valence: Cu2+Zn2+Mn4+3O8
Oxide of copper, zinc and
manganese
Crystal system: Orthorhombic
Specific gravity: 5.174 calculated for the empirical formula
Hardness: 5
Streak: Dark grey with a brownish tint
Colour: Black
Luminescence:
Solubility: Insoluble in room-temperature concentrated hydrochloric acid
Environments
Almagreraite is a new mineral, approved in 2025 and to date (August 2026) reported only from the type
locality.
Localities
At the type locality, República Romana mine, Sierra Almagrera, Cuevas del Almanzora, Almería, Andalusia, Spain,
the mines exploit hydrothermal vein-type deposits containing base-metal sulphides and Pb-Sb-Cu-Ag sulphosalts. They
date back to the period of Phoenician colonisation and were worked extensively for lead and silver during Roman
times.
Almagreraite was found on the mine dump, where it occurs as tapering prisms or blades up to about 0.4 mm in
length, commonly forming subparallel to divergent aggregates. It is a
secondary mineral associated intimately with well
crystallised blades of malachite on a matrix consisting of well
crystallised goethite and massive friable
hematite. Crystals of almagreraite are black and opaque with
submetallic lustre. The tenacity is brittle and the fracture is splintery
(MM 90.3.608-614, Mindat).
Almagreraite from República Romana mine -
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