Copiapite
Nowadays, the importance of Copiapite is undeniable in our daily lives. Whether due to its historical relevance, its impact on society or its influence on different aspects of our lives, Copiapite has captured the attention and interest of many people around the world. In this article, we will fully explore everything that Copiapite represents, its evolution over time, and its relevance today. Through a detailed analysis, we will examine the different aspects that make Copiapite a topic of great importance and interest to a wide audience. Join us on this journey through the history, meaning and relevance of Copiapite, and let's discover together why it is a topic that deserves our attention.
| Copiapite | |
|---|---|
 Copiapite from the Bolesław Mine, Kłodzko District, Lower Silesia, Poland | |
| General | |
| Category | Sulfate minerals |
| Formula | Fe2+Fe3+4(SO4)6(OH)2·20(H2O) |
| IMA symbol | Cpi[1] |
| Strunz classification | 7.DB.35 |
| Crystal system | Triclinic |
| Crystal class | Pinacoidal (1) (same H-M symbol) |
| Space group | P1 |
| Unit cell | a = 7.337 Å, b = 18.76 Å, c = 7.379 Å; α = 91.47°, β = 102.18°, γ = 98.95°; Z = 1 |
| Identification | |
| Color | Sulfur-yellow to orange when crystalline, greenish-yellow to olive-green when massive |
| Crystal habit | Tabular pseudo-orthorhombic platy crystals, typically in scaly incrustations or granular pulverulent aggregates |
| Twinning | Contact twins |
| Cleavage | Perfect on {010}, imperfect on {101} |
| Fracture | Irregular/uneven, micaceous |
| Tenacity | Fragile |
| Mohs scale hardness | 2.5–3 |
| Luster | Pearly on {010} |
| Diaphaneity | Transparent to translucent |
| Specific gravity | 2.04–2.17 |
| Optical properties | Biaxial (+) |
| Refractive index | nα = 1.506 – 1.540 nβ = 1.528 – 1.549 nγ = 1.575 – 1.600 |
| Birefringence | δ = 0.069 |
| Pleochroism | X = Y = pale yellow to colorless; Z = sulfur-yellow |
| 2V angle | Measured: 45° to 74°, Calculated: 48° to 72° |
| Solubility | Soluble in water |
| References | [2][3][4][5] |
Copiapite is a hydrated iron sulfate mineral with formula: Fe2+Fe3+4(SO4)6(OH)2·20(H2O).[3] Copiapite can also refer to a mineral group, the copiapite group.
Copiapite is strictly a secondary mineral forming from the weathering or oxidation of iron sulfide minerals or sulfide-rich coal. Its most common occurrence is as the end member mineral from the rapid oxidation of pyrite. It also occurs rarely with fumaroles. It occurs with melanterite, alunogen, fibroferrite, halotrichite, botryogen, butlerite and amarantite.[3] It is by far the most common mineral in the copiapite group.
It rarely occurs as single crystals, is in the triclinic crystal system, and is pale to bright yellow. It is soluble in water, changing the water color to deep orange or orangish-red. In solution copiapite is very acidic. In high concentrations a negative pH can occur, as reported in waters draining from Richmond Mine at Iron Mountain, California.[4] Copiapite can easily be distinguished from native sulfur because it does not give off an odor when dissolved in water. It can be distinguished from similar appearing uranium minerals, such as carnotite, by its lack of radioactivity. The only way to differentiate between the minerals in the copiapite group is by X-ray diffraction.
Copiapite was first described in 1833 for an occurrence near Copiapó, Atacama, Chile.[5] It is sometimes known as yellow copperas. Other occurrences are in California, Nevada, and in the filled paleo sinkholes and caves of Missouri.
See also
References
- ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
- ^ Mineralienatlas
- ^ a b c Handbook of Mineralogy
- ^ a b (Nordstrom and Alpers, 1999)
- ^ a b Mindat.org
