Baron Richthofen pursued science purely out of natural curiosity - and like many amateurs, he achieved impressive success. While still a geologist (later Ferdinand von Richthofen retrained as a geographer), the baron voiced the concept of “rhyolite” - liquid stone. This happened in 1861.
In the same year, another German geologist, Justus Roth, explored the magmatic outpourings of the island of Lipari and coined the name “liparite” to designate the acidic rocks formed from lava outpourings.
Liparite and rhyolite, described by mineralogists, coincided so precisely in composition and properties that both terms came into use. Currently, the name “liparite” is considered obsolete, and it is recommended to use the word “rhyolite” to designate silicate rocks of volcanic origin.
Rhyolite: composition and form
Rhyolite is not necessarily formed from lava, but certainly from products of volcanic activity. Heavy gas-saturated magma, having reached the surface of the planet, can stop its movement at the stage of formation of a volcanic dome, and this dome will consist of rhyolite.Pyroclastic flows, settling on the ground in thick layers of volcanic ash, quickly cake and set, forming the same rhyolite.
Pumice, the result of rapid cooling of silicate melt in ocean water, is another form of rhyolite. And other variations on the theme of volcanic glass - obsidian, perlite, pechstein - also belong to rhyolites.
In addition to silica, rhyolite usually contains feldspar and quartz. Common impurities are pyroxene, plagioclase, and jasper. Occasionally, small inclusions of biotite are observed in rhyolites. Hornblende in rhyolites crystallizes into needle-shaped formations.
In terms of mineralogical and chemical composition, rhyolite is very similar to granite.
Sometimes rhyolite is beautiful
Due to the high content of silicon oxide, rhyolite is usually light in color (usually grayish), and its structure is glassy. Gases released but not evaporated make rhyolite porous - although more often this rock has a fine-grained structure. 
Metal oxides, the impurity concentration of each of which can reach half a percent, and for iron and aluminum - several percent, can give rhyolites various shades of brown color. There are yellow and even pink rhyolites.
Certain varieties of rhyolites (such as porphyries) have considerable decorative advantages and are used in architecture. However, for the most part, rhyolite chips are used as a filler in the asphalt concrete mass.
Rhyolites with a silica content of more than 70% are used as raw materials for glass production. The slab form of occurrence of rhyolites provides raw materials for the production of natural facing materials.
Lava outpourings often occur in areas heavily strewn with debris. In these cases, valuable tuffs, breccias, and conglomerates can form.
Exotic rhyolite
Rhyolite that does not have amorphous or crystalline quartz inclusions is called felsite. Felsite is a light gray, fine-grained stone whose main attraction may be inclusions of pyrolusite. 
Manganese dioxide, which makes up pyrolusite, crystallizes to form mineralogical dendrites. The growths of pyrolusite crystals so reliably copy the shoots of small-leaved plants that they can easily be mistaken for plant fossils. In this connection, amateur mineral collectors sometimes begin to talk about the hollow Earth and plant remains brought to the surface by eruptions...
From the history : In 1861, Ferdinand von Richthofen introduced the concept of “rhyolite,” which translated from Greek means “flowing stone.” The name of the mineral comes from the Greek rhyah, meaning “flowing,” “lava,” or “flow,” and lithos, “stone.” Another name, liparite, arose in connection with the location of its discovery in the Aeolian Islands in Italy (1861, Justus Roth). In the same year, Justus Roth coined the term "liparite", used for the felsic effusive rock that characterizes the island. Lipari.
Liparite is a product of volcanic activity in which hot lava flow was erupted onto the surface of the earth and subjected to relatively rapid cooling. Elements of nature such as water, ice and the atmosphere stopped its further crystallization into granite. Liparit traditionally occurs in the form of domes or needles, less often - in the form of small covers or flows, layers, and produces bodies of more complex shape. Liparite can also form as ash accumulations. The formation of liparite may be accompanied by inclusions of clastic formations - for example, tuffs or other volcanic agglomerates. Liparite is often defined as volcanic glass with various impurities, or is given a catchy designation for the volcanic analogue of granite. The places where liparite (rhyolite) is mined are volcanic zones of the globe. Today liparite and rhyolite are considered synonymous....
Chemical composition : SiO - 72, 80; K2O - 4.46; Al2O3 - 13.49; Na2O - 3.38; Fe2O3 - 1.45; H2O - 1.47; CaO - 1.20; FeO - 0.88; MgO - 0.38; TiO2 - 0.33; P2O5- 0.08; FeO - 0.88 (% by weight)...
Liparites may contain from 50% to 100% volcanic glass. Inclusions of dark-colored minerals are quite rare. Porphyry inclusions, as a rule, are represented by various feldspars - quartz, sanidine, plagioclase. Very rarely and in small quantities there may be inclusions of biotite or hornblende. Biotite inclusions in the rhyolite structure visually resemble shiny leaves, and hornblende traditionally has the form of needle-shaped or elongated crystals.
The structure of liparite in the main mass will be glassy or porphyritic, less often it will be cryptocrystalline or fine-grained formations with a fine-porous texture. Liparite is formed during the solidification process of magma that flows from the depths of volcanoes, so the structure of the stone can be formed by a combination of tiny crystals, gas bubbles or cracks, internal planes and glassy inclusions. The flow of lava often results in a streaky or fluid texture.
Impurities: feldspars, quartz, pyroxene, plexiglass, biotite.
Texture: porous...
Specific gravity: 2.3 - 2.4...
Hardness: 5...
Fracture: conchoidal..
Gloss: oily, resinous, glassy...
Color: Traditionally, the color of liparite is represented by white, yellowish or light gray shades. Less common are specimens with a pinkish color. Note that varieties of liparite, the bulk of which is glassy, can be visible in areas of a thin layer. It is known that glassy varieties of liparite are also characterized by a black, bluish-gray or greenish-gray, reddish color. Very rarely, such varieties of liparite are painted white.
Varieties of liparite(rhyolite) Depending on the structural features or inclusions in the composition of liparite, there are different varieties of this rock. For example, liparite without quartz inclusions is called felsite. A glassy variety with a dark color (from brown and brown to black), in the structure of which there are practically no inclusions, is called obsidian. Perlite is a shell-like variety of obsidian. Pumice is a porous, very light variety of liparite that forms through underwater eruptive processes. A variety of liparite, called pechtstein, is a volcanic glass with a characteristic resinous luster and color in brown, reddish, greenish, yellowish or black shades.
Application: It so happened that liparite did not find industrial application, with the exception of in certain cases (in construction and for glass production). In jewelry, the stone began to be used only in Lately and in a small amount...
But as an ornamental material, people have been using it for a long time. Thanks to its picturesque texture, which is very reminiscent of jasper, this stone can be found in the form of tumbling and cabochons in stores and at exhibitions under the trade name “oceanic jasper” or “Madagascar jasper”. Recently, this stone has gained popularity as an amulet, talisman, and talisman. Liparite (rhyolite) is a stone of harmony.
Lithotherapists consider Liparite a stone as a stabilizer of physical and mental state. It is good to use it as a preventive measure to prevent an impending illness or nervous disorder, as well as to ease the pain of the patient and give confidence in one’s strength.
Liparit is considered a kind of talisman for couples who are married or just about to enter into a relationship. It strengthens the relationship between people and protects family happiness. A figurine or sculpture made of liparite is an excellent gift for newlyweds, just lovers and more. The stone is well suited for people seeking constancy and stability in life, having noble aspirations and spiritual beauty.
Rhyolite is an igneous volcanic rock and is similar in composition to granite. This mineral is characterized by a glassy structure interspersed with quartz, plagioclase, and sanidine. The stone is also known by the obsolete name "liparite", as it was first discovered in the Aeolian Islands. Scientists later determined that rhyolite occurs in areas of volcanic activity across the planet in the form of lava flows, volcanic domes, or ash accumulations.
The material for the formation of rhyolite is not always lava, but it must be the products of volcanic activity. For example, heavy magma, saturated with gases, comes to the surface and stops at the moment of formation of a volcanic dome, the main component of which will be rhyolite. A pyroclastic flow can also deposit a thick layer of volcanic ash on the ground, cake and set to form rhyolites.
Today, rhyolite is mined in all places where there are volcanoes: in the Caucasus, in the Amur region and Kamchatka in Russia, in Ukraine, in Kazakhstan, in European countries and in the USA. At the same time, gems differ in external characteristics depending on their origin.
Geologist and geographer Baron Ferdinand von Richthofen in the mid-19th century formulated a description of a “liquid stone” called rhyolite. Around the same time, a scientist from Germany, Justus Roth, was studying magmatic outpourings on the island of Lipari and discovered acidic rocks that form from lava. According to the location of the find, the mineralogist named the stone liparite.
When scientists later compared both minerals, it turned out that they were absolutely identical. Now the name “liparite” is outdated, and it is recommended to call silicate rock of volcanic origin rhyolite.
The chemical composition of rhyolite is quite complex and is represented by a whole complex of oxides of silicon, titanium, aluminum, iron, magnesium, calcium, sodium, and potassium. Its main component is silica; it also contains feldspar and quartz. Among the impurities, pyroxenes, plagioclases, jasper, and biotite stand out.
At the fracture, the mineral is glassy or granular. With a Mohs hardness of 5, rhyolite is generally a brittle stone, unlike granites, which it resembles in chemical composition.
Samples with a high content of silicon oxide are distinguished by light shades or gray color, and a glassy structure. Gases that are released but not evaporated during the formation of rhyolite create the porous structure of the mineral.
Rhyolite with admixtures of various metal oxides looks impressive due to its rich color palette, which includes white, shades of dark green, red, gray, yellow.
Types of rhyolite
Taking into account the structural features and inclusions in the composition of rhyolites, several subspecies are distinguished for this mineral:
- Rhyolite, which does not contain impurities of quartz of an amorphous or crystalline structure, is called felsite. This is a light gray mineral with a fine-grained structure, which may contain pyrolusite as an impurity.
- Obsidian is a glassy subspecies colored in dark tones: from brown and brown to black; there are practically no foreign inclusions in its structure.
- Perlites are a subspecies of obsidian that looks like a shell.
- Pumice is a porous and very light rhyolite, the formation of which occurs during the processes of volcanic eruptions under water.
- Pechtstein is a volcanic glass that has a characteristic resinous shine, colored brown, reddish, greenish, yellowish or black.
Rhyolite is an excellent talisman for all lovers; the stone symbolizes the constancy of feelings. Its energy is aimed at maintaining tenderness, love and trust. After all, every married couple On its way, it will certainly encounter some obstacles and difficulties, and it is rhyolite that will help in any such situation to maintain warm and sincere relationships. Rhyolite crafts are often presented to couples on their wedding day as a family amulet.
In addition, rhyolite helps its owner in broadening his horizons, gaining peace of mind and harmony.
Rhyolite has a stabilizing effect on the psychological and physiological state of a person. It is not able to cure any disease on its own, but it can stop its development, relieve pain and help the body recover faster.
Some of the subspecies of rhyolite are endowed with good decorative properties and have found application in architecture. Rhyolite, deposits of which are formed in the form of slabs, is used in the production of natural facing material. Rhyolite crumbs are used as a filler for asphalt concrete mixtures.
Rhyolite, which contains more than 70% silica, is used as a raw material in glass production.
In cases where lava outpouring occurred in an area abundantly strewn with clastic material, valuable tuffs, breccias, and conglomerates are formed.
Basic tones in color scheme Rhyolite is white, yellowish or light gray in color. Specimens painted in shades of pink are less common.
Subspecies of rhyolite with a glassy structure are often translucent on a thin layer. Such varieties of the mineral are characterized by colors such as black, bluish-gray and greenish-gray, reddish, depending on the presence of certain impurities. Such white samples are often found.
Rhyolite is distinguished by the fact that the natural specimen always retains a pleasant feeling of coolness. Even if the jewelry with it was in the box along with other stones, rhyolite still remains a little colder than other gems. At the same time, if you take the gem in your hands, it heats up very, very quickly - in seconds.
Rhyolite is a fragile gem that must be protected from mechanical stress, cracks and scratches. To clean it, use warm soap solution and a soft brush, after which the product is washed with cool running water and polished soft cloth.
Astrologers say that rhyolite is suitable for representatives of all zodiac signs, but it is most favorable towards Sagittarius, Aries, Scorpio and Leo. Cancer, Capricorn and Virgo should pay attention to a subtype of this mineral - obsidian, which will become a talisman for attracting success and good luck.
In general, rhyolite is suitable for anyone who strives for stability, loves to help other people and is not afraid to set even the most incredible goals.
Rhyolite beads, made up of small pebbles, can be purchased for $10 to $15. Rings, earrings and pendants with large stones are priced from $20 and up.
- Rhyolite crystals formed in the form of a mineralogical dendrite are occasionally found. Such growths externally resemble plant shoots with small leaves, and are often mistaken for plant fossils.
- Rhyolite is formed under very high temperatures, and its destruction is also possible only when heated above 1200 °C.
rhyolite-kainotype effusive rock of acidic composition of the normal series from the rhyolite family, in which phenocrysts of quartz, plagioclase N 5-15, sanidine (sometimes biotite, hornblende, magnetite) are immersed in the groundmass. The groundmass is glassy or microfelsitic, less commonly spherulitic. The content of volcanic glass is from 50 to 100%. Fine-grained analogue of granite. Diagnostics. Uneven, rough fracture . Texture. Glassy. The term rhyolite was coined in 1861 by Richthofen from the Greek word for “flowing.” Yu. Roth in the same 1861 introduced the term “liparite” for the acidic effusive rocks of the island of Lipari. Currently, the main term is rhyolite, and liparite is considered an equal synonym.
Varieties. Rhyolites, a cenotype effusive rock rich in silica (68-77%); has a porphyritic structure, containing phenocrysts of quartz, potassium feldspar, plagioclase, and less commonly biotite or pyroxene, embedded in a glassy groundmass, usually of a fluid texture. Obsidian is a glassy (almost without phenocrysts) variety of liparite. They are often dark, brown, brown and black in color. Perlites are shell-like varieties of obsidians. Pumice is a light, very porous, light acidic outpoured rock. Pumice is a product of underwater outpourings. Pechsteins are black, red, brown, greenish, sometimes yellowish, less often white volcanic glasses with a resinous sheen.
Form of occurrence. It occurs in the form of lava flows, volcanic domes, and ash accumulations.
Practical significance. Used to cover roads and for construction purposes.
exam card No. 4
1. Depth-thermodynamic diagram of the distribution of metamorphic facies and characteristics of mineral parageneses of the corresponding rocks.
facies of catagenesis - metagenesis. Lithogenesis corresponds to the second facies - facies of porphyritic shales
facies Greenstones (altered porphyrites) and phyllites, silky shale with sericite and clayey material (hydromica and pyrochlorite).
Greenschist facies: muscovite-chlorite and biotite-chlorite subfacies (higher temperature)
Epidote amphibolites and two-mica gneisses (muscovite and chlorite)
facies of amphibolites and biotite gneisses
migmatites, pyroxene-plagioclase schists and gneisses
Temperature-facial indicators - polymorphic modifications of Al silicate (Al2SiO5) (disten-region metham, andalusite-contact met-m, sillimanite - transitional indicator to ultrametamorphism of the 5th and 6th facies)
Bukhites – contact, devitrified rocks
Granulite and eclogite facies. Capture the top of the mantle.
2. Characteristics of statistical mathematics methods used in mineralogical and petrographic studies.
In mineralogy, during analytical studies, a calculation is formed with the initial data, which is a set of observed (measured) values of a random variable (mineral, metal content, etc.), characterized by some distribution function. The values of a random variable usually change. They are characterized by the dispersion of a random variable - a measure of its dispersion around the arithmetic mean, which is determined by the formulas
When studying source data in mineralogy, the following three tasks are usually set:
1. Identification and interpretation of correlations between quantities.
2. Classification of ores by material composition.
3. Selection of a method for predicting technological indicators based on the material composition of ores.
To identify connections between values, correlation analysis is used, as a result of which correlation coefficients (paired) are determined, which are a measure of the linear relationship between two random variables:
At r = 0 there is no dependence between random variables. It is considered established if the correlation coefficient in absolute value differs from zero, which is established using an approximate condition.< 0, то обратная.
The significance limit of the correlation coefficient can be determined from the tables, where it depends on the number of samples (vertically) and on the confidence probability (across horizons). If r > 0, then the relationship between random variables is direct (as the values of one value increase, the values of the other increase), if r
Correlation coefficients are widely used to approximate the relationship between processing quality indicators.
The correlation coefficients are combined in the form of a correlation matrix - a table of paired correlation coefficients between random sample variables, in which the number of rows is equal to the number of columns.
In 1861, Ferdinand von Richthofen introduced the concept of “rhyolite,” which translated from Greek means “fluid.” In the same year, Justus Roth coined the term "liparite", used for the felsic effusive rock that characterizes the island. Lipari. Today liparite and rhyolite are considered synonymous.
Liparite is a type of volcanic rock. It is rich in silica and contains inclusions of feldspar, quartz and other minerals. The most common impurity is feldspar. One of the most known varieties, which has practically no inclusions - obsidian.
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Properties and structure of liparite |
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| Chemical composition: | SiO - 72, 80; K2O - 4.46; Al2O3 - 13.49; Na2O - 3.38; Fe2O3 - 1.45; H2O - 1.47; CaO - 1.20; FeO - 0.88; MgO - 0.38; TiO2 - 0.33; P2O5- 0.08; FeO - 0.88 (% by weight) |
| Mixing: | feldspars, quartz, pyroxene, plexiglass, biotite and jasper |
| Color in daylight: | light, almost white, yellowish, light gray |
| Color under artificial light: | doesn't change |
| Shine: | oily, resinous |
| Texture: | porous |
| Specific gravity: | 2,3 - 2,4 |
| Transparency level: | opaque |
| Hardness: | 5 |
| Kink: | conchoidal |
| Synonym: | rhyolite |
Most often, the mineral is found in light shades, usually white porous crystals. The mineralogical composition of the stone is similar to granite, from which it differs in origin.
Liparite deposits
Liparite rock is found all over the world where there has ever been active volcanic activity. In Russia, its deposits are found in the Caucasus, Kamchatka, Altai, in Europe - in the foothills of the Alps, in America - in the Cordillera. The deposits are represented by lava flows, ash accumulations or volcanic domes.
Practical use
Liparite is a building stone, used in the manufacture of glass and for covering roads. Some quartz porphyries, for example Altai ones, have decorative properties and are used as ornamental stones.
