Pararealgar
Pararealgar is a mineral with formula As₂S₃, in the Sulfuros group. This specimen comes from Cavnic Mine, Cavnic, Maramureș, Transilvania, Rumanía and joined the Terrium collection in 2025.
Description
Complex hydrothermal polymetallic piece in which, at first glance, realgar (red), pararealgar (the most abundant), orpiment (yellow), galena (metallic cubic crystals) and quartz (specifically cryptocrystalline quartz: chalcedony) occur together. With a more careful look or under a hand lens, pyrite, sphalerite, chalcopyrite with bluish iridescence and even native arsenic are clearly present.
History of this specimen
It came out of the back of a van at a market stall, sold almost as if passing contraband, with glances to both sides, on the promise that I would not say I bought it there and with the boast that even a university had asked that person for specimens for use in their laboratories. Despite its industrial, even chromatically aggressive, appearance, it is a fragile piece that must be handled with care.
About Pararealgar
An arsenic-bearing assemblage with no single dominant species. Realgar and its close relative orpiment display the unmistakable palette of reds, oranges and yellows, but the effect is fragile: colour is the main virtue and light its arch-enemy. Contrary to common claims, realgar does not transform into orpiment (As₂S₃) but into pararealgar. Light gradually reorganises its internal structure; the crystal becomes stressed, its volume increases and it collapses into a yellow powder which, although it retains the composition of realgar (As₄S₄), has a completely different crystal structure and with it a different name. It is then a dimorph. Around it, intergrown galena and sphalerite, with pyrite, chalcopyrite, chalcedony and even native arsenic, complete the scene.
About the locality
A world-famous mining locality and an absolute classic for this paragenesis. The polymetallic hydrothermal veins of Cavnic are known for producing very complex associations where blood-red realgar grows on heavy sulphide matrices.
Technical data
- Catalogue No.
- 0311
- Composition
- As₂S₃
- Name
- Pararealgar
- Group
- Sulfuros
- Category
- Meritum Persé
- Matrix
- cuarzo
- Associations
- realgar, pararealgar, arsénico, pirita, calcopirita, galena
- Mine
- Cavnic Mine
- District / Municipality
- Cavnic
- Province
- Maramureș
- Region
- Transilvania
- Country
- Rumanía
- Size (cm)
- 10 x 5.5 x 4
- Weight
- 110 g
- Acquired
- 2025
- Ex-collection
- Pablo M
- Etymology
- From the Latin "auripigmentum", 'golden pigment', after its characteristic yellow-golden colour.
- Quality
- Buena
- Value trend
- Estable
Related specimens
- Acantita (Paramórfica tras Argentita) — Marruecos
- Calcopirita (Irisada) — Francia
- Cinabrio — Eslovenia
- Cinabrio — España
- Esfalerita (Cleiofana o Blenda acaramelada) — España
- Esfalerita — España
- Esfalerita (Cleiofana o Blenda acaramelada) — España
- Esfalerita (Cleiofana o Blenda acaramelada) — España