AugiteAugite is isomorphous with the minerals Diopside and Hedenbergite. It is an intermediarymember between these minerals, forming a series, but contains additional sodium and aluminum within its chemical structure. Strictly speaking, because of the variables in its chemical structure, Augite is really more of a group then a single mineral, but it is still classified a single mineral species by the IMA.
Augite is an important rock-forming mineral, and large crystals are fairly common. It is the most widespread member of the pyroxene group, and it frequently alters to many other minerals, including Hornblende, Chlorite, and Epidote. When altered to Actinolite, it is often called Uralite. Augite usually occurs in dull crystals that are ugly and uninteresting. Occasionally, though, it is found in large lustrous crystals which are sought after by mineral collectors. The name Augite is derived from the Greek word augites, "brightness", in reference to the bright luster this mineral occasionally exhibits. http://www.minerals.net/mineral/augite.aspx HornblendeHornblende is a complex inosilicate series of minerals (ferrohornblende – magnesiohornblende).[3] It is not a recognized mineral in its own right, but the name is used as a general or field term, to refer to a darkamphibole.
Hornblende is an isomorphous mixture of three molecules; a calcium-iron-magnesium silicate, an aluminium-iron-magnesium silicate, and an iron-magnesium silicate.As an exciting, colorful mineral, hornblende doesn't make the list.Hornblende is the most common member of the amphibole family of silicate minerals. Besides silica, it has a little bit of everything else in its chemistry: ferrous and ferric iron, aluminum, calcium, manganese, magnesium, and alkalis. Hornblende forms prismatic, dark brown to black, small crystals in many igneous rocks. It is most commonly confused with the mineral augite that forms shorter, stubby crystals. Hornblende can be distinguished from augite by its cleavage; the two cleavage planes in augite are nearly at right angles, while the two cleavage planes in hornblende are at an angle of 124 degrees. (no website) RhodoniteRhodonite is well known among collectors for its beautiful pink and red color. The red variety can be so deep red that it rivals the color of Ruby. The large crystals once found in Franklin, New Jersey, are classic rarities that make magnificent reference pieces.
Rhodonite often has black manganese oxide veins running through a specimen, giving it the distinct appearance of pink with black crisscrossing lines and flower-like formations throughout. These are the forms most commonly used as gemstones, especially in beads and ornamental objects. Large massive specimens of black-streaked Rhodonite is often sliced and polished into slabs for collectors. http://www.minerals.net/mineral/rhodonite.aspx TremoliteTremolite and Actinolite are two very similar minerals that form a series with each other and essentially share the same chemical formula. Tremolite has a greater presence of magnesium over iron, whereas Actinolite has a greater presence of iron over magnesium.
Tremolite and Actinolite share several recognized varieties. Mountain Leather, a thickly fibrousand leathery variety, has a silky luster, a soft felt-like feel, and elastic fibers. Nephrite, another fibrous variety, is made up of tough, interlocking fibers, so dense that the fibers are not discernible. Actinolite and Tremolite both contain a form of asbestos which is made of movable and elasticfibers. Actinolite asbestos is less common; most forms are in fact Tremolite. This form of the mineral contains significant health hazards and should never be brought near the mouth. If its fibers or particles enter the lungs, they can cause asbestosis. Asbestosis is a lung disease caused by inhalation of asbestos particles, which causes several cancers, particularly lung cancer and mesothelioma. Symptoms of asbestosis do not arise until about 20 years after the inhalation. Due to the hazards, washing hands after handling specimens is highly recommended. Many mineral collectors avoid collecting asbestos minerals out of safety concerns. http://www.minerals.net/mineral/tremolite.aspx |
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