Hornblende: properties, composition and application

One of the most common minerals, related to rock-forming, is hornblende. This is a common name for amphiboles, formed from two German words - "horn" and "dazzle." In the split form, the crystals of this mineral look like a horn.

External description and properties

The external appearance of hornblende makes it easy to identify it among other minerals. It is distinguished by fused short-columned crystals with hexagonal or rhombic cross-section. It is a fairly hard opaque mineral with a small specific gravity and unique cleavage. The hardness index is 5.5-6 on the mineralogical scale. Density hornblende - an average of 3,100 to 3,300 kg / m³. Cleavage is noted in two directions at an angle of 124 degrees.

Hornblende does not differ in its coloration. It can be from light green to brownish-black (usually it is basalt rocks with a high content of alkaline compounds). Minerals of any color have equally beautiful glass, semimetallic with shimmering shine. This rock is not exposed to acids. With strong heating, it can fuse into a dark green glass.

Chemical composition

It is unstable and varies within fairly wide limits. The ratio of aluminum to trivalent iron varies, as well as magnesium to bivalent iron. Perhaps the predominance of potassium over magnesium. In the presence of a high content of titanium (up to 3%), the mineral is called "basaltic hornblende." The composition is generated depending on the set of chemical elements, among which potassium oxide can be from 10 to 13%, ferric oxide - from 9.5 to 11.5%, iron oxide - 3-9%, magnesium oxide - 11-14%, Sodium oxide - 1.5%, silica - 42-48%, aluminum oxide - 6-13%.

In the process of weathering, the rock decomposes into opals and carbonates. Interaction with hydrothermal solutions leads to the transformation of the mineral into chlorite, epidote, calcite and quartz.

Under the influence of various physical factors, the rock can undergo complex chemical processes, leading to the formation of intermediate compounds.

Origin

Hornblende is a rock-forming mineral and the main component of amphibolites, shales and gneisses. It occurs, as a rule, in the process of exposure of pegmatites to igneous rocks. In volcanic ash is sometimes found in the form of single crystals. In the form of primary material in the outcrops on the surface of rocks, this mineral is rare.

Ordinary hornblende, the description of which is given above, can be transformed into basaltic. This occurs usually in lava flows, under oxidizing conditions and heating to a temperature of 800 ° C. This process is quite easy to create artificially.

Place of Birth

Large crystals of hornblende are rare, and therefore of great interest to collectors. They are observed mainly in gabbro pegmatites, which are not so many. In the Urals, in the vicinity of Mount Sokolina, well-formed crystals up to 0.5 m in length are found. Very beautiful specimens of this mineral are found in the Czech Republic, Norway, and in the volcanic lava of Vesuvius in Italy.

Hornblende is widespread in the Ore Mountains of Germany, rich in calc-silicate rock. The syenite massif Meissen is known for its rich deposits of this mineral. Large deposits of crystals are located in Burma.

Scope of application

The main use of this mineral found in the industry. At certain technological processes has hornblende properties to transform into calcite, epidote, quartz, chlorite, to form carbonates and opals during decomposition. It is used as raw material for manufacturing dark green glass, as well as in construction in granite.

Fragility and lack of external attractiveness do not allow using this mineral in jewelry business. But the inclusion of hornblende in quartz products makes it possible to create a beautiful stone, whose brilliance and shape can be admired.

There is a hornblende in the mineral with the name "tears of Apaches", which is a kind of obsidian. It is believed that this stone has the ability to help a person cope with various misfortunes, attracts luck.

Specialists who study lithotherapy, talk about the positive effect of the mineral on the immune system, digestive and excretory. It's enough just to wear jewelry from it - beads, pendants, etc.