Carminite

A rare arsenate mineral with a bright red colouration, and which takes its name from its colour – ‘carmine red’.

Can form extremely detailed, sharp crystals with a bright red colour – unfortunately, they are rather small and will primarily be of interest to micromineral collectors.

Toxic mineral: contains lead, arsenic. 

Information about Carminite

Carminite is a rare secondary lead iron arsenate hydroxide mineral, and one that earns its place on any wishlist of secondary arsenate minerals for the sheer vividness of its colour: deep carmine-red to brick-red acicular crystals with a silky lustre, forming dense radiated tufts and elongated sprays on arsenate-bearing gossan, are among the most intensely coloured of all secondary minerals.

The colour – which gives the mineral its name directly – is rare in the mineral kingdom and shared only by a handful of species.

It forms acicular to prismatic crystals, typically very elongate and hair-like, in radiated fibrous groups and silky tufts, deep carmine-red to dark red or brick-red, occasionally pale red or pinkish. The lustre is silky to vitreous.

It forms in the oxidised zones of lead-arsenic bearing hydrothermal ore deposits, where circulating oxidising groundwater breaks down arsenopyrite and galena to release arsenate and lead simultaneously.

 

Uses and History

Carminite has no industrial or gemological applications. It is collected as a mineral specimen for its striking colour.

The mineral was first described from the Louise Mine, Germany.

The finest collector specimens come from the Tsumeb Mine in the Otjozondjupa Region of Namibia, which has produced the largest and most vibrantly coloured carminite crystals known, some reaching several millimetres in length, on gossan and smithsonite matrix.

Additional localities include Broken Hill in New South Wales, Australia; the Clara Mine at Oberwolfach in Baden-Württemberg; and the Ojuela Mine at Mapimí in Durango, Mexico.

There are several locales around the UK, primarily in Cornwall and Cumbria, although they primarily produce micro crystals.

 

Mineralogy

Chemistry
A lead iron arsenate hydroxide with the formula PbFe2(AsO4)2(OH)2. Orthorhombic. Member of the palermoite group. Secondary arsenate mineral in oxidised lead-arsenic ore deposits.
Colours and Variations
Deep carmine-red to brick-red or dark red; occasionally pale red to pinkish. The vivid carmine colour is diagnostic.
Streak
Pale red to pinkish-orange
Lustre
Silky to vitreous
Transparency
Translucent
Fracture
Irregular; perfect cleavage parallel to crystal length
Tenacity
Brittle
Crystal habit
Acicular to prismatic, very elongate; radiated fibrous tufts and sprays; silky aggregates on gossan matrix
Mohs hardness
3.0 – 3.5
Fluorescence
Non-fluorescent
Specific Gravity
5.4 – 5.6 (notably high for a red mineral)
Easiest testing method
The deep carmine-red acicular silky fibrous habit, combined with notably high specific gravity for its colour and the lead-arsenic ore deposit context, is essentially diagnostic for carminite in hand specimen. Few red minerals share this combination of needle-like silky habit and high density. Definitive identification requires X-ray diffraction.

Hazards and Warnings

Highly toxic mineral: contains lead and arsenic. Both lead and arsenic compounds are seriously toxic. Mineral collectors must wash their hands thoroughly after handling, must not inhale any dust, and must keep specimens away from children. Do not use any carminite specimen near food or drink.

Almost all rocks, minerals (and, frankly, almost all other substances on earth) can produce toxic dust when cutting, which can cause serious respiratory conditions including silicosis. When cutting or polishing rocks, minerals, shells, etc, all work should be done wet to minimise the dust, and a suitable respirator or extraction system should be used.

 

Translations

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  • Carminita

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English:

  • Carminite

Italian:

  • Carminite

Russian:

  • Карминит

French:

  • Carminite

Japanese:

  • カルミナイト

Spanish:

  • Carminita

German:

  • Karminit

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Further Reading / External Links