Apr 30 2014
Cechite was named after Dr. Frantisek Cech (1929–1995), who was the Head of the Department of Mineralogy at the Charles University in Prague, Czech Republic. Cechite belongs to the descloizite group.
Properties of Cechite
The following are the key properties of cechite:
- Cell Data
- Space group: Pnam
- a = 7.605(3)
- b = 9.435(4)
- c = 6.099(2)
- Z = 4
- Crystal Data
- Orthorhombic
- Point group: 2/m2/m2/m
- Crystals are rough and rounded to 3mm, elongated along [001], showing {110} and {010}
- As aggregates of anhedral crystals in granular masses
- X-ray powder pattern: 3.228 (100), 2.625 (81), 5.119 (77), 2.908 (77), 2.663 (53), 4.249 (51), 3.345 (42)
- Chemical Composition
| Elements |
Content 1 |
| PbO |
53.97 |
| V2O5 |
22.88 |
| FeO |
15.15 |
| MnO |
4.56 |
| H2O |
2.58 |
| CaO |
0.29 |
| As2O5 |
0.29 |
| Sb2O5 |
0.16 |
| ZnO |
0.12 |
| Total |
[100.00] |
- Optical Properties
- Anisotropism: Perceptible to strong; pale gray to dark gray, with brownish tint
- Bireflectance: Weak to imperceptible
- Optical class: Biaxial
- R1–R2: (400) —, (420) 17.0–19.3, (440) 16.3–18.9, (460) 16.0–18.5, (480) 15.6–18.3, (500) 15.4–18.1, (520) 15.1–17.8, (540) 14.8–17.6, (560) 14.6–17.6, (580) 14.4–17.7, (600) 14.4–18.0, (620) 14.5–18.3, (640) 14.8–18.6, (660) 15.1–18.9, (680) 15.2–18.8, (700) 15.3–18.7
- Estimated Properties
| Electron density |
Bulk density (electron density) = 5.21 g/cm3
note: Specific gravity of cechite = 5.99 g/cm3 |
| Photoelectric |
PE Cechite = 934.40 barns/electron
U=PE Cechite x ρ electron density= 4,865.89 barns/cm3 |
| Fermion index |
Fermion index = 0.11
Boson index = 0.89 |
Radioactivity
|
Cechite is not radioactive
|
How to Identify Cechite
Cechite can be identified in the field by its black color. Its opaque form has no cleavage. This mineral has a sub-metallic luster with a black streak. The fracture on this mineral is brittle and uneven. The density of cechite is 5.88 g/cm3 with a hardness of 4.5-5 – approximate to near apatite. The mineral is magnetic.
Global Distribution
Cechite is distributed in the following places:
- Czech Republic - From Vrancice, about 15 km south-southeast of Pribram
- Italy - Liguria, Savona Province, Magliolo, Isallo
- USA - Nevada, Humboldt Co. Iron Point District, Valmy, Silver Coin Mine
Occurrence of Cechite and Useful Mineral Association
Cechite occurs on specimens from old mine dumps from a polymetallic ore deposit. It is often associated with minerals such as hedyphane, hematite, willemite, quartz, and calcite.
References