Mineral Betafite
The chemical composition of the mineral Betafite is indicated by the formula (Ca,Na,U)2(Ti,Nb,Ta)2O6(OH,F), Calcium Sodium Uranium Titanium Niobium Tantalum Oxide Hydroxide Fluoride. This Betafite belongs to the Oxides and Hydroxides mineral class. The Oxides mineral class, of course with the inclusion of the Hydroxides, is considered as a rather diverse class. This class usually includes corundum or minerals that are appear quite hard. Those minerals that are quite soft like psilomelane are also included in this Oxides and Hydroxides mineral class. Some gemstones such as spinel, chrysoberyl and corundum and some other metallic minerals like hematite also belong in this mineral class. Many Oxides and Hydroxides minerals appear black but some can be found in a very colorful appearance. It has been considered that the large diversity of the Oxides and Hydroxides mineral class can be partially attributed to the great abundance of the oxygen, which can be found in the crust layer of the Earth. It has been found that oxygen comprises almost over 45% of the crust layer of the Earth by weight. Most oxygen are chemically found locked up in some other more complex minerals based on their chemical complex ions like PO4, BO3, NO3, CO3, SO4, SiO4 and many others. But a single oxygen ion has many opportunities to combine with various elements in many different ways. In a strict sense they say, those minerals that belong to the more complex mineral classes like the silicates are really Oxides. But mineralogists made Oxides and Hydroxides mineral class to comprise all non-complex minerals containing oxygen or hydroxide. This is so because it would be cumbersome for them to be able to deal with only four different mineral classes such as the elemental class, the sulfides class, the halides class and the extremely diverse mineral class, the Oxides and Hydroxides together with its many subclasses and comprising almost 90% of all minerals. This Oxides and Hydroxides mineral class comprises minerals containing mostly ionic bonds and this is considered as a helpful distinguishing factor for its members because most complex minerals of other classes contain typical covalent bonds in nature. Take Quartz for instance, its chemical composition is indicated by the formula SiO2. Quartz would be considered an Oxide but because of its covalent silicon oxygen bonds it was classified to belong in the silicates mineral class, in a tectosilicates group to be specific. The positive one (+1) state of hydrogen is considered as a single proton and is so small that when combined with oxygen it would disappear into the oxygen and results to the OH group, which is almost of the same size as a single oxygen ion with negative two (-2) charge. The OH group can actually fit into many crystal sites in which oxygen would otherwise occupy, but only with a negative one (-1) charge. Adding negative charges or fewer positive charges can do the balancing of the crystal.
Betafite mineral is also a member of the Pyrochlore group. This Pyrochlore group of minerals commonly includes some obscure, unusual and isometric oxides. This group is composed of basically three minerals and members of their respective subgroups. Members of this Pyrochlore group commonly have the general formula that is indicated by A1-2B2O6(O,OH,F)-nH2O. The A in the general formula can be either lead, calcium, bismuth, barium, potassium, sodium, tin, cerium, strontium, cesium, uranium, antimony, yttrium, thorium, and/or zirconium. The B on the other hand represents a different position in the chemical structure and can be either iron, tin, niobium, titanium, tungsten and/or tantalum. The general formula of the Pyrochlore group is found very closely related to and also considered isometric to the Stibiconite group. Although they are found closely related, the two groups are different with respect to their general crystal habits. The Pyrochlore group is known to form crystals that are usually fine in form, which are commonly found crystallizing in the isometric system of crystallization. The Stibiconite group on the other hand rarely forms good crystals.
Mineral Betafite is considered as a popular uranium-bearing mineral for most serous mineral collectors. This Betafite is one of those uranium-bearing minerals, which are known to form nice, splendid and well-shaped crystals. Betafite minerals have rare earth elements such as thorium in its chemical formula. Betafite is also considered as one of the rare earth oxides. There are other rare earth oxides, which display similar properties to each other but usually lack the well-formed isometric crystals of Betafite. These rare earth oxides are the aeschynite, fergusonite, samarskite and euxenite.
Betafite minerals are commonly considered as popular and interesting minerals. Its large and well-formed crystals make up for its popularity even if it lacks color. Mineral Betafite is known to crystallize in the isometric symmetry class. It usually forms large octahedral and dodecahedral crystals that are found weighing up to 100 kilograms. Frequently, they can be modified by some other isometric forms and/or flattened when two opposing faces are found dominating the crystal. Those well-formed Betafite crystals are considered classics in the mineral world. Betafite mineral is commonly associated with several other minerals such as rocks quartz, allanite, feldspars, zircon, columbite, thorite, tantalite, biotite, fergusonite and some other rare earth minerals.
Mineral species Betafite was first discovered in the year 1912 at Ambolotara, Betafo Department, Antananarivo Province, Madagascar. This Betafite mineral was named after the type of locality. Betafite mineral is synonymous with Samiresite, Blomstrandite and Mendeleyevite.
Betafite mineral specimens are usually found black in appearance and commonly with a tint of yellow, green or brown. Betafite commonly shows earthy to metallic luster in reflected light of petrographic polarizing microscopes. They may sometimes appear vitreous when crystals appear translucent. Betafite is found having an absent cleavage when mineral specimen is evaluated under several adjustments on the aperture diaphragm of the polarizing light of a geological microscope. The fracture found for mineral specimen Betafite is commonly found conchoidal when it is viewed with the aid of a petrographic polarizing light microscope. Conchoidal fractures are developed in brittle materials characterized by smoothly curving surfaces. Fracture describes how a mineral breaks when broken contrary to its natural cleavage planes. The hardness measure of Betafite mineral specimen using the Mohs scale method is usually found ranging from 4 to 5.5. When specimen of Betafite mineral is rubbed on a white porcelain streak plate, it usually leaves a yellow to brown streak. The specific gravity measure of Betafite commonly gives an approximate value usually found ranging from 3.7g/cm³ to 5.0g/cm³, which is commonly considered heavy for non-metallic and average for metallic minerals. The extreme variation is caused by variable composition of components metals.
Betafite crystals are generally found opaque in appearance. But some Betafite minerals are also found as translucent specimens. Betafite minerals are commonly found crystallizing in the isometric system, which can be seen clearly visible under a polarizing light microscope for geologists. This isometric system comprises crystals having three axes, all of which are perpendicular to one another and all are found equal in lengths. Crystal habits of Betafite commonly include octahedral and dodecahedral crystals, which are often modified by other isometric forms and/or flattened when two opposing faces are found dominating the crystal, which can be seen clearly visible when viewed under a polarizing microscope. They can be also found in granular forms and also as massive crystals, which commonly shows splendid microscope image under a polarized light microscope. These are the common texture observed in granite and other igneous rocks. Betafite mineral specimens are often found with a yellow or green earthy coating. Betafite crystals can be also found as encrustrations that are commonly formed as crust-like aggregates on matrix, which commonly shows magnificent microscope views under a polarizing light microscope. Betafite minerals are usually found isotropic when viewed between crossed nicols of polarizing light geological microscope. The interference color found is almost colorless under petrographic polarizing microscope. Aside from using a geological microscope, a polarized light microscope can also be used. Betafite commonly shows a high surface relief when viewed with the aid of a polarized light microscope. Betafite minerals are considered radioactive and it is highly recommended that they must be stored away from other minerals that are subject to damage from radioactivity. Human exposure should also be limited.
Betafite mineral specimens are commonly found forming in rare earth rich granite pegmatites. They can be also found in a slow cooling igneous intrusive rock such as the ones that are found from the site Betafo, Malagasy Republic in Madagascar. It can be also possibly found in the contact metamorphic marbles that surround these pegmatites. Best field indicators of Betafite minerals usually include color, crystal habit, fracture, environment, radioactivity, luster, specific gravity and its splendid association with some other interesting minerals. Betafite minerals notably occur at some types of localities including Silver Crater Mine, Bancroft in Ontario, Canada and Brazil as well as Russia, Spain, Peru, India, Pakistan, Norway, California, New Mexico, Arizona and Colorado, USA.
