Ransomite
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Ransomite is a
sulfate The sulfate or sulphate ion is a polyatomic anion with the empirical formula . Salts, acid derivatives, and peroxides of sulfate are widely used in industry. Sulfates occur widely in everyday life. Sulfates are salts of sulfuric acid and many ...
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 The mineral pyrite (), or iron pyrite, also known as fool's gold, is an iron sulfide with the chemical formula Fe S2 (iron (II) disulfide). Pyrite is the most abundant sulfide mineral. Pyrite's metallic luster and pale brass-yellow hue giv ...
, 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 The Mohs scale of mineral hardness () is a qualitative ordinal scale, from 1 to 10, characterizing scratch resistance of various minerals through the ability of harder material to scratch softer material. The scale was introduced in 1812 by th ...
. Ransomite occurs as needle-like crystals and has radiating tufts and crusts. Ransomite has perfect cleavage along the plane. The specific gravity is 2.632 g/cm3.


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 The sulfate or sulphate ion is a polyatomic anion with the empirical formula . Salts, acid derivatives, and peroxides of sulfate are widely used in industry. Sulfates occur widely in everyday life. Sulfates are salts of sulfuric acid and many ...
that has a similar formula to the mineral Cuprocopiapite. Cuprocopiapite has a
specific gravity Relative density, or specific gravity, is the ratio of the density (mass of a unit volume) of a substance to the density of a given reference material. Specific gravity for liquids is nearly always measured with respect to water at its densest ...
of (2.23 g cm−3), which is close to the value of Ransomite.


Chemical composition


X-ray crystallography

Ransomite is in the
monoclinic In crystallography, the monoclinic crystal system is one of the seven crystal systems. A crystal system is described by three vectors. In the monoclinic system, the crystal is described by vectors of unequal lengths, as in the orthorhombic s ...
crystal system. The
space group In mathematics, physics and chemistry, a space group is the symmetry group of an object in space, usually in three dimensions. The elements of a space group (its symmetry operations) are the rigid transformations of an object that leave it uncha ...
associated with Ransomite is ''P21/b'' with unit cell dimensions: a = 4.811 Å, 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

{{Authority control Lead minerals Monoclinic minerals Minerals in space group 11 Sulfate minerals Wikipedia Student Program