Tsumebite

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Rare phosphate mineral

title: "Tsumebite" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["phosphate-minerals", "lead-minerals", "copper(ii)-minerals", "monoclinic-minerals", "minerals-in-space-group-11"] description: "Rare phosphate mineral" topic_path: "general/phosphate-minerals" source: "https://en.wikipedia.org/wiki/Tsumebite" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Rare phosphate mineral ::

::data[format=table title="Infobox mineral"]

Field	Value
name	Tsumebite
category	Phosphate minerals
image	Tsumebite-278446.jpg
imagesize	260
caption	Tsumebite from the Bluebell Claims, California, US.
formula
IMAsymbol	Tsu
molweight	685.99 g/mol
strunz	8.BG.05
dana	43.4.2.1
system	Monoclinic
class	Prismatic (2/m)
(same H-M symbol)
symmetry	P21/m
color	Emerald-green, green in transmitted light
habit	Crusts of intergrown crystals on matrix
twinning	Almost always twinned. Twins may be multiple, with serrated re-entrants.
cleavage	None
fracture	Uneven
tenacity	Brittle
mohs
luster	Adamantine to vitreous
refractive	Nx = 1.885 to 1.900, Ny = 1.920, Nz = 1.942 to 1.956
opticalprop	Biaxial (+)
pleochroism	Faint: X = Y = very pale blue to colorless; Z = robin’s-egg-blue
streak	Green
gravity	6.13
solubility	Readily soluble in HCl and slowly soluble in .
diaphaneity	Transparent
references
::

The brackebuschite group

The minerals in the brackebuschite group have the general formula and crystallise in the monoclinic system, space group P21/m. The group includes:

Structure

The structure of the brackebuschite group minerals is composed of B-(O,OH)6 octahedra, two non-equivalent TO4 tetrahedra, TO4(1) and TO4(2), and two different irregular polyhedra of large cations. B and T represent different elements in different members of the group. Chains formed from the B octahedra link through the oxygens of TO4(2) tetrahedra, while the large cation polyhedra form double chains parallel to the b crystal axis through edge sharing with TO4(1) tetrahedra. The result is a tight three-dimensional structure. In tsumebite copper ions occupy the B sites, and phosphorus and sulfur occupy the T sites. Lead is the large cation.

Unit cell

Tsumebite belongs to the monoclinic crystal class 2/m, meaning that it has one twofold axis of symmetry perpendicular to a mirror plane. The space group is P 21/m, meaning that the crystal lattice is a primitive lattice, with structural elements only at the vertices of the unit cell. These structural elements are made up of two formula units (Z = 2).

Unit cell parameters are a = 8.69 Å, b = 5.78 Å, c = 7.86 Å, β = 111.87° or a = 8.70 Å, b = 5.80 Å, c = 7.85 Å, β = 111.5°.

Optical properties

Tsumebite is an emerald-green color, transparent and green in transmitted light, with a green streak and an adamantine (diamond-like) to vitreous (glassy) luster. It is biaxial (+) with refractive indices Nx = 1.885 to 1.900, Ny = 1.920 and Nz = 1.942 to 1.956. It is faintly pleochroic with X = Y = very pale blue to colorless and Z = robin's-egg-blue.

Physical properties

The mineral typically occurs as crusts of intergrown crystals on matrix. Cleavage is absent, but twinning is almost universal, and twins may be multiple, with serrated re-entrants. It is brittle, with an uneven fracture, hardness and specific gravity 6.13. It is readily soluble in hydrochloric acid HCl and slowly soluble in nitric acid HNO3. It is not radioactive.

Environment

Tsumebite is a rare secondary mineral in the oxidised zone of some arsenic-bearing lead-copper deposits, with other lead-bearing phosphates and sulfates. Associated minerals include azurite, smithsonite, malachite, cerussite, mimetite, wulfenite and olivenite. The type locality is the Tsumeb mine, Tsumeb, Otjikoto Region, Namibia. The Handbook of Mineralogy states that the type material was destroyed by bombing, but does not indicate when or where.

Tsumebite occurs at Morenci, Arizona, predominantly as twinned crystals associated with wulfenite, olivenite and the hyalite variety of opal.

References

LaForge (1938) American Mineralogist: 23: 772

References

Warr, L.N.. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine.
American Mineralogist (1966) 51: 258–259 and 267
[http://www.handbookofmineralogy.org/search.html Handbook of Mineralogy]
[http://www.mindat.org/min-4040.html Mindat.org]
Gaines et al (1997) Dana’s New Mineralogy Eighth Edition, Wiley
[http://www.webmineral.com/data/Tsumebite.shtml Webmineral data]
At [[Broken Hill, New South Wales]], Australia, tsumebite has been found as lustrous pale blue to bluish green crystals. It usually occurs with yellow crusts of [[corkite]]-[[hinsdalite]], colorless to white [[pyromorphite]] needles and sprays of pale greyish green [[zinc]]ian [[libethenite]]. Less commonly found with [[scholzite]] and [[torbernite]].Australian Journal of Mineralogy (1997) 3-1:53

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