Plata Arborescente
Plata is a mineral with formula Ag, in the Elementos nativos group. This specimen comes from Mina Bouismas, Tata, Tinghir, Drâa-Tafilalet, Marruecos and joined the Terrium collection in 2009.
Description
Arborescent crystals of native silver on a massive milky calcite matrix crossed by an actinolite band. In some areas, dark metallic masses appear, attributable to the allargentum-dyscrasite field.
History of this specimen
These specimens first appeared between 2009 and 2010, travelled to Tucson, and then disappeared from the market until the summer of 2025, when a few emerged from hiding and entered other collections. Almost all of them were acid-etched to free the silver from its calcite matrix.
About Plata
Sometimes native silver from Bouismas does not occur alone: it forms part of a silver-rich paragenesis linked to the silver-antimony system, with phases such as allargentum and dyscrasite. Dyscrasite is the silver antimonide with the most clearly defined composition, Ag₃Sb (three silver atoms for each antimony atom). Allargentum, by contrast, has a variable composition and is usually expressed as Ag₁₋ₓSbₓ or, approximately, as ~Ag₆Sb. These phases explain the dark metallic areas and give these silver specimens a higher mineralogical interest than a simple silver on calcite.
About the locality
The Bouismas Mine is known for hydrothermal veins rich in silver and associated sulphides. From mid-2008 to spring 2010 a limited suite of exceptional silver specimens like this one and also pseudomorphs of dyscrasite to allargentum. Mining has been halted and nothing is being produced now.
Technical data
- Catalogue No.
- 0139
- Composition
- Ag
- Name
- Plata
- Variety
- Arborescente
- Group
- Elementos nativos
- Category
- Cupidium
- Matrix
- Calcita
- Associations
- allargentum, discrasita, actinolita
- Mine
- Mina Bouismas
- District / Municipality
- Tata
- Province
- Tinghir
- Region
- Drâa-Tafilalet
- Country
- Marruecos
- Size (cm)
- 6.5 x 5.5 x 4
- Weight
- 25.2 g
- Acquired
- 2009
- Etymology
- From Latin "platus" (broad, extended) and the modern derivative "plata", referring to its characteristic lustre and colour.
- Quality
- Muy buena
- Value trend
- Al alza
Related specimens
- Acantita (Paramórfica tras Argentita) — Marruecos
- Andradita (Melanita) — Marruecos
- Apatito — Marruecos
- Aragonito — Marruecos
- Arfvedsonita — Marruecos
- Arsénico (Nativo) — Alemania
- Azurita — Marruecos
- Azurita — Marruecos