Mineral Buttgenbachite
The chemical composition of mineral Buttgenbachite is indicated by the formula Cu19(NO3)2Cl4(OH)32-2H2O, a Hydrated Copper Nitrate Chloride Hydroxide. This Buttgenbachite belongs to the Carbonates mineral class. These Carbonates minerals are commonly found deposited in marine settings after the settling and accumulation of the shells of dead planktonic life on the sea floor. They can be also possibly found in karst regions and in evaporitic settings like the Great Salt Lake found in Utah, where caves, stalactites, and stalagmites form due to the dissolution and reprecipitation of carbonates. The Carbonates class of minerals is known to include the borate and nitrate minerals.
Carbonate minerals contain basic anionic or negatively charged unit forming threefold symmetry where at the center resides either a nitrogen, boron or carbon atom, or an oxygen atom is found sitting at every corner of the structure. Typical carbonates are commonly found in transparent crystals, which are usually lightly colored when viewed and evaluated in transmitted light of polarizing light microscopes and other reflected light microscopes. They commonly show white streak when mineral samples are rubbed on a streak plate. Density measure is often found average above average. They are commonly soft and usually soluble to some degree in acidic solutions. They commonly exhibit good to perfect cleavage between crossed nicols of polarized light microscope, which is one of the many reflected light microscopes. Carbonate minerals tend to originate in oxidizing and sedimentary environments but with exception of carbonatite igneous intrusions.
Buttgenbachite is also a nitrate mineral. It is actually considered a rare copper nitrate mineral that is usually found displaying a very attractive and interesting microscope images under a polarized light microscope. Buttgenbachite is closely related to connelite, a sulfate mineral. Connelite and Buttgenbachite are isostructural minerals. Isostructural means they share the same chemistry and they have similar crystal habits and color, which are seen clearly visible when they are evaluated with the aid of geological microscopes. This connelite is actually a secondary mineral, which can be found in some unusual copper deposit oxidation zones. Connelite is also considered as a classic mineral from the copper mines of Arizona in the United States and Cornwall, England. Mineral Buttgenbachite on the other hand is much rarer than connelite. It can be only found in limited types of localities. Buttgenbachite was first discovered in the year 1925 at Likasi, Shaba that is now of the Congo. This locality is the only known place of discovery until its existence was proven through the laboratory results of the few samples of the mineral species from South Comobabi Mountains in Pima County, Arizona. Buttgenbachite mineral species was actually named after Henri Buttgenbach (1874-1964), a Belgian mineralogist.
Buttgenbachite minerals are commonly found in a deep blue color in transmitted light of geological polarizing light microscope, another type of reflected light microscopes. They are usually found exhibiting a vitreous luster in reflected light of petrographic polarizing light microscope. It actually has absent cleavage even when evaluated with the aid of polarizing microscope for geologists. When mineral specimen of Buttgenbachite is evaluated between crossed nicols of petrographic polarizing microscope, it commonly displays an uneven fracture. The hardness measure of Buttgenbachite mineral specimen using the Mohs scale method is commonly 3. When mineral specimen Buttgenbachite is rubbed on a white streak plate, it is usually found leaving a blue streak. The specific gravity measure of Buttgenbachite commonly gives an approximate value ranging from 3.4g/cm³ to 3.5g/cm³, which is considered slightly above average for non-metallic minerals.
Buttgenbachite minerals are known to crystallize in the hexagonal system, which can be seen clearly visible with the aid of geological microscopes. The hexagonal system of crystallization comprises crystals having four axes. Three of which are positioned in a single plane with equal length and are symmetrically spaced. The fourth axis is found to be perpendicular to the other three axes. The Buttgenbachite crystals are commonly found translucent to transparent in appearance. The crystal habit of mineral Buttgenbachite usually include acicular to fibrous crystals, which are arranged in tufts, layers or radial aggregates and are commonly found exhibiting splendid and interesting microscope images under a petrographic polarizing microscope. Crystals of Buttgenbachite may also appear striated parallel to elongation or as radiating sprays and felt-like masses. Buttgenbachite minerals are commonly associated with other fascinating minerals such as quartz and several other copper minerals.
Buttgenbachite minerals are actually uniaxial positive figures. When specimens of Buttgenbachite are evaluated between crossed nicols of petrographic polarizing light microscope, they are commonly found having refractive indices ranging from 1.738 to 1.752. It has a maximum birefringence at 0.014. Buttgenbachite also shows a high surface relief under geological polarizing light microscopes.
Buttgenbachite minerals can be actually found in some oxidation zones of the copper deposits. The best field indicators of mineral Buttgenbachite usually include color, crystal habit, locality and its majestic association with other minerals. Buttgenbachite minerals have limited occurrence at the famous localities of Likasi, Shaba, which is now of the Congo and the South Comobabi Mountains in the Pima County at Arizona, USA.
