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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. 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.

Occurrence

Ransomite is found in association with pyrite, voltaite, and romerite. These minerals can be found in Campbell shaft, Arizona. 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.

Physical properties

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. 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/cm.

Optical properties

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.

Chemical properties

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.

Chemical composition

X-ray crystallography

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.

References

1. ^ Wood, M.M., 1970, The Crystal Structure of Ransomite, The American Mineralogist, v. 55, p.729-734
2. ^ Hudson Institute of Mineralogy, 2023, Ransomite: https://www.mindat.org/min-3364.html (accessed November 2023)
3. ^ Mineral Data publishing, 2001-2005, Ransomite: https://www.handbookofmineralogy.org/pdfs/ransomite.pdf (accessed November 2023)

• Lead minerals
• Monoclinic minerals
• Minerals in space group 11
• Sulfate minerals