Jamesonita
Jamesonita is a mineral with formula Pb₄FeSb₆S₁₄, in the Sulfosales group. This specimen comes from Mina Quiruvilca, Distrito de Quiruvilca, Santiago de Chuco, La Libertad, Perú.
Description
The 'Darwin's Prof' one. Aggregate of fine, lustrous, dark-grey acicular jamesonite crystals on white barite matrix. Dense, radiating texture covering much of the piece, with sea-urchin-like sprays. A hand-lens piece.
About Jamesonita
Jamesonite is a lead, iron, and antimony sulfosalt. It has a highly directional crystal structure: it is as if its internal architecture had "rails" that favor growth along its length far more than its width. That is why its crystals always tend to elongate. At Noche Buena, this growth is taken to the extreme, producing thousands of hair-thin crystals; in this Quiruvilca piece, by contrast, the crystals grew thicker and developed in radial clusters from different points. The result is rigid, metallic needles forming small stars. It is the exact same crystal structure expressed in two completely different ways.
About the locality
Mina Quiruvilca (from Quechua "Sacred Tooth") is a giant of the Andes at 3,800 m that is now in a tragic state. After the bankruptcy of the formal operation in 2017, the mine fell into legal limbo and was taken over by informal mining. It is now an "every-man-for-himself" zone, with violent conflicts over control of the galleries and no safety. This brought the careful extraction of collector specimens to an abrupt halt. Quality pieces, like this one, are survivors from the mine's "golden age", and what remains is finite.
Technical data
- Catalogue No.
- 0248
- Composition
- Pb₄FeSb₆S₁₄
- Name
- Jamesonita
- Group
- Sulfosales
- Category
- Meritum Persé
- Matrix
- Barita
- Mine
- Mina Quiruvilca
- District / Municipality
- Distrito de Quiruvilca
- Province
- Santiago de Chuco
- Region
- La Libertad
- Country
- Perú
- Size (cm)
- 7 x 3.5
- Etymology
- Named in honour of Robert Jameson, an influential (and somewhat obstinate) Scottish mineralogist who was a professor at the University of Edinburgh and had a very famous student: Charles Darwin. The relationship was disastrous. Darwin wrote in his autobiography that Jameson's lectures were so "incredibly boring" that they made him hate geology for years. Jameson was old-school—he believed all rocks formed in water ("Neptunism")—and refused to accept the new volcanic theories.
- Quality
- Buena
- Value trend
- Estable
Related specimens
- Barita — Perú
- Barita — Perú
- Cuarzo — Perú
- Jamesonita — México
- Jamesonita — Perú
- Oropimente — Perú
- Rodocrosita — Perú
- Rodocrosita — Perú