Mimetita
Mimetita is a mineral with formula Pb₅(AsO₄)₃Cl, in the Arseniatos group. This specimen comes from Yanga Koubenza Quarries, Mfouati, Mfouati District, Bouenza Department, República del Congo and joined the Terrium collection in 2026.
Description
Vertical floater of yellow mimetite with stalactitic growth, the surface covered by very tightly packed, lustrous crystals. The piece shows vivid colour, high lustre and a distinctly columnar aspect, with irregular but natural terminations at both ends.
History of this specimen
I keep it as a set with pyromorphite (0300) and vanadinite (0298).
About Mimetita
One of the three lead chlorapatites. Mimetite is a lead chlorarsenate, very close structurally to pyromorphite and vanadinite. The three form a well-recognised visual and chemical family: mimetite with arsenic, pyromorphite with phosphorus, and vanadinite with vanadium.
About the locality
Yanga Koubenza: episodic mineralisation, small pockets and a high loss rate of specimens. Oxidised deposit in gossans with narrow, fragile cavities, where crystals grow in confined spaces and are commonly recovered damaged. Mining prioritises tonnage over preservation, which explains the scarcity of intact pieces. Mimetite, discovered in the area in 2024, is concentrated in a very localised sector and shows an unusual diversity of habits and colours by world standards, although most specimens are small and require intensive preparation.
Technical data
- Catalogue No.
- 0299
- Composition
- Pb₅(AsO₄)₃Cl
- Name
- Mimetita
- Group
- Arseniatos
- Category
- Estélites
- Mine
- Yanga Koubenza Quarries
- District / Municipality
- Mfouati
- Province
- Mfouati District
- Region
- Bouenza Department
- Country
- República del Congo
- Size (cm)
- 2.9 x 1.8 x 1.2
- Weight
- 8.4 g
- Acquired
- 2026
- Etymology
- From the Greek "pyro" (fire) and "morphé" (form), for changing colour on heating.
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