There are no straight lines in nature? But look at the pyrite crystals.
Pyrite is sulfur, or iron, pyrite. The name of pyrite - this iron sulfide (FeS2) - comes from the Greek word "feast" - fire. The ancient Greeks called it - fire-like - for its fiery yellow color and the ability to strike sparks when struck by solid (steel, flint) objects.
The second name - "sulfur pyrite" - came from the Middle Ages: this is how miners and naturalists called sulfides of copper, iron, arsenic and other chemical elements, which have a bright metallic luster.
Crystals are most often represented by cubic, pentagon-dodecahedral and octahedral habit.
Crystals of pyrite are of perfect shape in the host mass of quartz.
Fe S2
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System cubic
Hardness 6.5 on the Mohs I0-point scale of hardness
Specific gravity 5
No cleavage
Fracture fracture
Yellow color
Powder color gray
Metallic gloss
The ancient Egyptians, noticing that pyrite is highly polished, used it to make jewelry and mirrors. In the Middle Ages, the mineral was widely popular in Europe under the name "Alpine Diamond".
Pyrite jewelry was especially popular in France. They were adorned with shoe buckles, garters, bracelets, watch cases and even sun umbrellas. But the decorations quickly darkened, and in a humid environment, oxidation of pyrite led to the formation of a brown, loose mineral limonite - what we call "rust" in everyday life.
The Spaniards - the first explorers of America - called pyrite "the stone of the Incas" because pyrite was a special honor among the Indians. In the burials of Indian leaders, polished pyrite tablets were often found, probably serving as mirrors (a controversial issue). Pyrite is widespread in nature. It occurs in the form of large, fine-grained masses and well-crystallized forms. In most ore deposits, the mineral is extracted along the way with other minerals.
Pyrite is used as a raw material for the production of sulfuric acid. In some deposits, impurities are extracted from it: gold, silver, cobalt and other chemical elements. Iron and sulfur are obtained from pyrite. During combustion, iron oxide is obtained, from which the metal is extracted. Sulfur is recovered after combustion and sulfuric acid is obtained.
It is impossible to find a place on the globe where pyrite is found - it is all over the planet. But really good examples are extremely rare. The best and largest crystals and aggregates are formed from hot (hydrothermal) underground solutions.
Pyrite in the Moscow region is found in the form of separate small crystals, small clusters and thin veins in flints, for example, in the Peskovsky quarry, as well as in the nodules of phosphorites in Voskresensk. In the latter, instead of pyrite, another crystallographic variety of iron sulphide is observed - marcasite, which looks like pyrite.
Pyrite is called the companion of gold. It is always present where the precious metal is (but not vice versa). The constant presence of pyrite in gold deposits, strong metallic luster and bright yellow color make it look like gold. In the old days, pyrite was jokingly called "cat's gold".
English-speaking peoples call pyrite "fool's gold" - "stupid gold", or "gold for fools." Pyrite is harder than gold - it won't scratch with a knife. In mineralogical museum collections, whole showcases are often dedicated to pyrite. He always attracted people's attention.
The traditional, most common form of pyrite crystals is cube. When an uninitiated person sees samples of pyrite from the Akchatau deposit in Kazakhstan or the Navajo deposit in Spain, he cannot believe for a very long time that ideally formed cubes with absolutely mirror-like edges were not carved and polished by man, but created by nature itself.
Crystals of pyrite from the Astafyevsky crystal-bearing deposit in the South Urals have a peculiar shape. This is an octahedron. "Octa" - eight, "hedra" - face: the pyrites of the Astafyevskoe deposit have the shape of an octahedron.
In addition to the traditional cube, the so-called "pentagondodecahedron" is always present in the birch pyrite. "Penta" is five, "gonion" is an angle, "dodeca" is twelve, and "hedra" is a facet. Translated into understandable Russian:-) "pentagondodecahedron" means "a crystal with twelve pentagon-shaped faces."
The faces of cubic pyrite crystals from the Berezovsky deposit are always covered with fine shading, and the strokes of one face are always strictly perpendicular to the strokes of the neighboring face. In the state of Illinois (USA), you can find samples of pyrite with a radial-radiant structure, reminiscent of small "suns", where each ray forms a strongly elongated crystal.
The Americans themselves call such formations "pyrite dollar". In sedimentary rocks, pyrite often replaces plant and animal remains, forming spectacular fossils: pyritized ammonite shells, pieces of wood, and even fragments of trunks and other parts of trees.
Such processes can be very fast. There is a known case when the body of a miner who died in a deep mine was completely replaced by pyrite in just 60 years. This happened in Sweden in the 13th century.
Pyrite can form:
1) In liquation-magmatic deposits (as well as in associated pneumatolytic and hydrothermal formations) in a variety of igneous rocks;
2) by hydrothermal means in skarn ores in vein deposits with galena, pyrrhotite, sphalerite, chalcopyrite, gold and other minerals;
3) in volcanic exhalations, subvolcanic rocks and hydrothermal pyrite deposits (together with chalcopyrite, etc.);
4) in a variety of sedimentary rocks, together with other minerals.
Often, beautiful pyrite crystals are found in clays and shales. The most remarkable crystals in terms of cut and size are found in hydrothermal and metasomatic deposits.
In the Urals - Bezezovskoye gold deposit, Central Kazakhstan - Akchautskoye. Large deposits of Pyrite are concentrated in deposits of hydrothermal origin, especially in sulfur pyrite deposits, sedimentary and metamorphic rocks. In sedimentary rocks, pyrite is formed in enclosed sea basins like the Black Sea as a result of the precipitation of hydrogen sulfide. In addition, pyrite is formed in small quantities during magmatic processes.
It often forms pseudomorphs based on organic remains (wood and various organisms). It is unstable on the earth's surface, and over time, pyrite crystals are destroyed, oxidizing to limonite. Satellite minerals: native elements (gold, bismuth), oxides (quartz, cassiterite, magnetite), silicates, sulfides (especially marcasite), fluorides (fluorite). In sedimentary rocks - opal, siderite, barite, marcasite. Main deposits: Russia, Norway, Sweden, France, Germany, Azerbaijan, USA. The largest supplier of the highest quality collectible pyrites in the world is Spain (Rio Tinto).
Sometimes Pyrite is formed in the form of radially-radiant intergrowths, which are called the Pyrite Sun or Pyrite Dollar. The only deposit where pyrite of this morphology is formed. Illinois (USA).