Mineral Caledonite

The chemical composition of mineral Caledonite is indicated by the formula Cu2Pb5CO3(SO4)3(OH)6, a Copper Lead Carbonate Sulfate Hydroxide. This Caledonite belongs to the Sulfates mineral class. Sulfates are known chemically to contain the sulfate anion with a charge of negative two. This mineral class commonly forms in evaporitic settings where evaporation of water with high saline content slowly occurs. Through this process, the formation of both halides and sulfates are allowed at the water-sediment interface. Sulfate minerals are known to commonly occur as gauge minerals in some hydrothermal veins systems along with sulfide ore minerals. These Sulfide ore minerals are commonly found exhibiting brilliant microscope image under an ore polarizing light microscope and other reflected light microscopes. They can be also formed as a secondary oxidation product of original sulfide minerals. The Sulfates class commonly includes minerals exhibiting interesting and attractive mineral specimens, which are usually splendid when viewed with the aid of petrographic polarizing light microscope. A typical sulfate mineral is usually vitreous in luster, with average hardness in Mohs scale, and usually has density that is considered average to above average. Some Sulfates are usually soluble and fluorescent in ultraviolet light.

It has been found that mineral Caledonite is quite difficult to classify due to the presence of both carbonate and sulfate anions in its chemical structure. But since it has been also found that it contains more sulfates than carbonates anions in its chemical formula, it has been classified as a Sulfate rather than a Carbonate mineral. Another pint of consideration is through the highest complexity and electronegativity of the mineral. Caledonite has been found possessing a more complex and stronger electronegative anion than the carbonate anion. Also due to the difference in their hydroxides and for the same reason, this Caledonite was not classified under Oxides and Hydroxides mineral class.

Caledonite crystals are commonly found in form of small and well-formed intricate crystals, which are very interesting to view under a polarizing microscope for geologists. Due to the lead content of the mineral Caledonite, it is commonly found exhibiting a nice luster. The attractive blue to green color that is commonly displayed by the mineral Caledonite in transmitted light of a geological microscope, which is one of many reflected light microscopes, is due to its copper content. Caledonite is also known as a close relative of mineral linarite. Mineral Linarite has a chemical formula indicated by CuPbSO4(OH)2. This mineral species Linarite is normally found displaying a deeper blue color, which is very interesting to view under polarizing light microscope. Mineral Linarite is commonly found in form of tabular or prismatic crystals. Tabular crystals are commonly found in shape like a book and the dominant faces of prismatic crystals are that of a prism. But these Linarite crystals are commonly found with slanted and non-symmetrical termination. Both Linarite and Caledonite minerals are formed in the oxidation zones of lead and copper ore deposits. Both minerals are known to make for outstanding and micromountable specimens that are usually found beautiful when evaluated under polarized light microscope.

Caledonite mineral species was actually first discovered in Scotland in the year 1832. Caledonite actually derived its name from the ancient and poetic name of Scotland, the Caledonia. Scotland is known as Caledonia in most literature especially in poetry. To be specific, Caledonite was first discovered at Leadhills, Lanarkshire in Scotland. This locality is actually a famous source of many usual, interesting and fascinating minerals. And Caledonite is one of them, which are commonly found exhibiting a nice, attractive and splendid image under polarizing microscopes. These Caledonite minerals are commonly associated with several interesting minerals such as cerussite, linarite, anglesite, malachite, brochantite and leadhillite.

Caledonite minerals are commonly found in shades of green, light blue, blue or blue green in transmitted light of petrographic polarizing light microscope. Caledonite mineral specimens are also found exhibiting a vitreous to resinous or greasy luster in of geological reflected light microscopes. When Caledonite mineral specimens are evaluated between crossed nicols of polarizing light microscope for geologists, they are commonly found having perfect basal cleavage in one direction and poor prismatic cleavages in two directions. The fracture that is found is usually uneven when Caledonite is examined under several adjustments on the aperture diaphragm of the petrographic polarizing light microscope. The hardness measure for mineral specimen Caledonite using the Mohs scale method is commonly found ranging from 2.5 to 3. When mineral specimen Caledonite is rubbed on a white porcelain streak plate, it is usually found leaving a greenish white to bluish green streak. The specific gravity measure of Caledonite mineral usually gives an approximate value ranging from 5.6g/cm³ to 5.8g/cm³, which is considered very heavy for translucent minerals.

Caledonite minerals are known to crystallize in the orthorhombic system, which can be seen clearly with the aid of geological microscopes. This crystal system comprises crystals having three mutually perpendicular axes, of which all are of different lengths. Specimens of Caledonite are commonly found transparent to translucent in appearance. The crystal habits of mineral Caledonite commonly include small micromountable prismatic crystals, which are usually less often found to be tabular in form. These crystals are commonly found with a truncation formed by the faces of multiple parallel domes and pyramids. They can be also found forming interlocking acicular crystals and also as radial aggregates. The individual Caledonite crystals can be actually found displaying a wide range of crystal faces. Caledonite crystals are commonly striated and they can be seen clearly visible when viewed with the aid of geological polarizing light microscopes. Caledonite crystals are also brittle, a property that is commonly displayed by glasses and most non-metallic minerals.

Caledonite minerals are biaxial negative figures as exhibited when they are evaluated between crossed nicols of petrographic polarizing light microscopes. Refractive indices of mineral specimen Caledonite are commonly found ranging from 1.818 to 1.909. The maximum birefringence of mineral Caledonite when viewed under polarized microscopes for geologists is usually found as 0.091. It has no dispersion found in transmitted light of geological microscopes. When mineral specimen Caledonite is evaluated between crossed nicols of geological polarizing microscope it is commonly found having very high surface relief. There is no specific data on the toxicity and health dangers for mineral Caledonite. However the specimens of Caledonite should be treated with great care and use of sensible precaution is advised upon handling them. Caledonite minerals have no industrial uses. They are commonly used as mineral specimens are they are also considered as very minor ore of copper and lead.

Caledonite minerals are commonly formed in secondary weathered zone of lead and copper ores. The best field indicators of mineral Caledonite usually include color, cleavage, crystal habit, streak, luster and density. Caledonite minerals notably occur at some types of famous localities such as the Leadhills in the Lanarkshire, Scotland and the Mammoth-St Anthony Mine, Tiger, Arizona where fine specimens of Caledonite are found. Several other localities are Chile, England, Italy and some areas in the United States like the Defense and Modoc mines and the Cerro Gordo Mine in the Inyo County, the Blue Bell Mine in the San Bernardino, California as well as in Beaver Creek, Utah and Dona Ana County in New Mexico.