Ransomite
| Ransomite | |
|---|---|
| General | |
| Category | Sulfate |
| Formula (repeating unit) | CuFe2(SO4)4*6H2O |
| Crystal system | Monoclinic |
| Crystal class | 2/m - Prismatic |
| Space group | P21/b |
| Unit cell | a = 4.811 Å, b = 16.217 Å c = 10.403 Å; β= 93.01°; Z = 2 |
| Identification | |
| Formula mass | 667.59 |
| Color | Bright sky blue; pale blue in transmitted light |
| Crystal habit | needle-like crystals |
| Cleavage | Perfect along {010} |
| Tenacity | Radiating tufts and crusts |
| Mohs scale hardness | 2.5 |
| Luster | Vitreous, pearly cleavage |
| Diaphaneity | Transparent |
| Density | 2.632 g/cm3 |
| Optical properties | Biaxial positive |
| Refractive index | nα= 1.631 nβ= 1.643 nγ= 1.695 |
| Birefringence | δ = 0.064 |
| Dispersion | v > r strong |
| References | [1][2][3] |
Ransomite is a sulfate mineral first discovered at the United Verde mine in Jerome Arizona. This mineral was formed as a result of a mine fire. The United Verde mine is one of few places in the world where Ransomite can be found. This mineral can be described as a soluble sulfate that forms needle-like crystals and has a pale blue color in transmitted light.[1] This mineral was named by Carl B. Lausen as a tribute to Frederick Leslie Ransome. Ransome was an American mining geologist who worked at the California Institute of Technology, the University of Arizona and the United states Geological Survey.[2]
Occurrence
[edit]Ransomite is found in association with pyrite, voltaite, and romerite. These minerals can be found in Campbell shaft, Arizona.[3] Ransomite tends to form in the cavities of crushed up rock in these different mines. In these cavities, Ransomite forms small radiating crystals and pale-blue crusts.[1]
Physical properties
[edit]Ransomite is a bright sky blue or a pale blue in transmitted light, transparent mineral with a vitreous, pearly luster. It exhibits a hardness of 2.5 on the Mohs hardness scale.[2] Ransomite occurs as needle-like crystals and has radiating tufts and crusts. Ransomite has perfect cleavage along the {010} plane. The specific gravity is 2.632 g/cm3.[2]
Optical properties
[edit]Ransomite is biaxial positive, this means it can refract light on two axes. The refractive indices are: α ~ 1.631, β ~ 1.643, and γ ~ 1.695 (Na). Dispersion is strong, v > r. Ransomite has a max birefringence of 0.064 and has a moderate surface releif. [2]
Chemical properties
[edit]Ransomite is a sulfate that has a similar formula to the mineral Cuprocopiapite. Cuprocopiapite has a specific gravity of (2.23 g cm−3), which is close to the value of Ransomite. [2]
Chemical composition
[edit]| Oxide | wt% |
|---|---|
| SO3 | 46.30 |
| Al3O3 | 1.52 |
| Fe2O3 | 22.57 |
| CuO | 11.29 |
| H2O | 18.82 |
| Total | 100.50 |
X-ray crystallography
[edit]Ransomite is in the monoclinic crystal system. The space group associated with Ransomite is P21/b with unit cell dimensions: a = 4.811Å, b = 16.217Å, c = 10.403Å; β= 93.01°; Z=2. Ransomite has a point group of 2/m and is prismatic. It also has skinny prisms extended parallel to the c axis. [2]
References
[edit]- ^ a b c Wood, M.M., 1970, The Crystal Structure of Ransomite, The American Mineralogist, v. 55, p.729-734
- ^ a b c d e f g Hudson Institute of Mineralogy, 2023, Ransomite: https://www.mindat.org/min-3364.html (accessed November 2023)
- ^ a b c Mineral Data publishing, 2001-2005, Ransomite: https://www.handbookofmineralogy.org/pdfs/ransomite.pdf (accessed November 2023)