Mineral Arsentsumebite
The chemical composition of mineral Arsentsumebite is indicated by the formula Pb2Cu(AsO4)(SO4)OH, Lead Copper Arsenate Sulfate Hydroxide. This Arsentsumebite belongs to the Phosphates mineral class. The Phosphates group of minerals commonly includes all minerals having a tetrahedral unit indicated by the formula AO4 with a negative three charge, where A can stand to be either antimony, arsenic, phosphorus or vanadium. The basic tetrahedral unit can be combined with other metal ions on a one to one ratio. Usually, it can be found in a more complex combinations with other ions such as the hydroxide groups with formula indicated by (OH), the uranyl groups with formula indicated by (UO2), a halogen or even water molecules. Apatite mineral is the most common phosphate, of which it is considered as an important biological mineral that is commonly found present in the teeth and bones of many animals. A typical phosphate mineral usually exhibits vitreous to dull luster in reflected light of polarizing microscope. Phosphate mineral specimens are often found strongly colored with density measure that is usually above average. The index of refraction found between crossed nicols of geological light polarizing microscope is usually low. The hardness found for most phosphate minerals is commonly at an average ranging from 4 to 7. Some other characteristics and properties vary for each kind of mineral.
Arsentsumebite mineral, although quite rare, is very popular among serious mineral collectors. This Arsentsumebite usually forms good and colorful mineral specimen, which are of fascinating and splendid appearance when evaluated with the aid of light polarizing microscopes for geologists. Tsumebite is one of the minerals, which is closely related to Arsentsumebite. These two minerals are commonly found in a series. A phosphate ion group in tsumebite replaces the arsenate ion group in the chemical structure of Arsentsumebite. Since the structures of these two minerals are the same, they are commonly found with slight difference from one another. Both Arsentsumebite and tsumebite minerals are formed in the oxidation zones of lead-copper ore deposits. These two minerals are commonly considered unusual for they both have two ions instead of the usual one ion that is found in most minerals. The chemical structure of Arsentsumebite contains an arsenate ion group and a sulfate ion group. Mineralogists preferably classify Arsentsumebite mineral as a phosphate because it can be noticed that the arsenate ion group has higher negative charge than the sulfate group. Arsentsumebite is commonly used as a mineral specimen, which is quite rare and yet very popular in the mineral world because of its fantastic microscope images in both transmitted and reflected light of geological light polarizing microscope.
Arsentsumebite derived its name from its chemical composition and structure as an Arsenate and from the name of its close cousin Tsumebite. This mineral species Arsentsumebite was first discovered in the year 1935 at the Tsumeb Mine or the Tsumcorp Mine, Tsumeb, Otjikoto Region, Namibia.
Arsentsumebite mineral specimens commonly appear in shades of green like yellow green and emerald green in transmitted light of petrographic light polarizing microscope. They have no cleavage found even when specimen is evaluated between crossed nicols of geological polarizing microscope. It commonly shows vitreous luster in reflected light of polarized microscope. Some guides present the luster of Arsentsumebite as Adamantine-metallic. The fracture found when mineral is evaluated with several adjustments on the aperture diaphragm of light polarizing microscope for geologists is commonly conchoidal. Chonchoidal fracture is a smooth curved fracture with concentric ridges of the type shown by glass. Fracture describes how a mineral breaks when broken contrary to its natural cleavage planes. They are usually brittle, a property generally displayed by glasses and most non-metallic minerals. The hardness measure for mineral Arsentsumebite using the Mohs scale method is only 3, which is considered soft and is not suitable for gemstone purposes. The specific gravity measure for this mineral gives an approximate value of 6.4g/cm³, which is considered heavy for translucent minerals. When Arsentsumebite mineral specimen is rubbed on a white streak plate, it usually leaves a light green streak.
Mineral Arsentsumebite is known to crystallize in the monoclinic crystal system. The monoclinic system of crystal formation comprises crystals having three axes of unequal lengths. Two of which are usually found in a position that is oblique or not perpendicular to one another. However, both of which are commonly found perpendicular to the third axis. Arsentsumebite crystals are usually found having transparent to opaque appearance. Crystal habits of mineral Arsentsumebite usually include tabular crystals, which are commonly found shaped like a book under geological microscopes. This tabular crystal formation can actually form twinned trillings. These minerals are actually found having complex twinnings when viewed with the aid of petrographic polarizing microscope. Some Arsentsumebite mineral specimens can be also found in crusts of distorted crystals. Arsentsumebite mineral is usually associated or found together with other minerals such as azurite, smithsonite and cerussite. Arsentsumebite is a biaxial negative figure. Arsentsumebite is found with very high surface relief when specimen is viewed between crossed nicols of petrographic light polarizing microscope. It also displays strong dispersion in polarized light of geological microscopes. After chemical evaluation, Arsentsumebite is found as a non-radioactive mineral. This Arsentsumebite mineral has no specific data on toxicity and health dangers. However, it is highly recommended that this mineral type should be treated with great care and use of sensible precautions is also advised upon handling them.
Arsentsumebite minerals are commonly formed in the oxidation zones of lead-copper ore deposits. It is a rare mineral usually found in the oxidized zone of a dolostone-hosted hydrothermal polymetallic ore deposit. It can be also found in a hydrothermal polymetallic barite-fluorite deposits. Occurrences of Arsentsumebite mineral is however limited to the locality of Tsumeb, Nambia and some other few areas like the Clara Mine near Oberwolfach, Black Forest, Germany. The best field indicators of Arsentsumebite commonly include locality, color, density, crystal habit and its awesome association with other colorful minerals.
