Myths and legends

What rocks contain calcite as their main mineral?

The name calcite comes from the Greek word meaning “lime.” Other names for the mineral and its varieties: stone flower, stone rose, paper spar, stalactite, stalagmite, heavenly stone, paper spar, anthraconite. physical properties a) color: white, yellow, pink, greenish,
b) hardness: 3,
c) density: 2,6 – 2,8 g/cm3,
d) degree of transparency: transparent (Iceland spar), translucent, opaque,
e) line – white, light gray,
e) gloss – glassy, ​​matte,
g) fracture – stepwise,
h) system – trigonal, ditrigonal-scalenohedral type of symmetry,
i) cleavage-perfect according to (1011). Calcite crystals have a wide variety of shapes: scalenohedral, lamellar, prismatic, columnar, rhombohedral. There are a lot of simple forms known, the main ones being (1010), (0112), (2131), (0001), (1011), (0221), (4041), (1120), etc. Doubles of (0001) are common. , (0112), including mechanical, polysynthetic according to (0221), occasionally according to (1011). Composition Formula – CaCO3. Chemical composition – content (in%): CaO – 56; CO4 – 44; impurities of iron, manganese, strontium, etc. are noted. Features of education. Various drusen and adhesions are observed. Granular dense calcite aggregates make up many hydrothermal veins, carbonatite bodies, and marble strata. Calcite is the main (and sometimes the only) mineral of carbonate sedimentary rocks, especially biogenic rocks, and, along with aragonite, is part of the solid parts of corals and many other organisms. It also forms stalactites, stalagmites, helectites and similar bushy aggregates in caves. Main deposits Dalnegorskoye field in Primorye, Evenkia. Medicinal properties In folk medicine, there is an opinion that calcite can alleviate diseases of the digestive system. The effect of the mineral on the diseased organ depends on the color of the stone. For example, orange calcite improves digestion and helps with spleen pathology. Red calcite helps with intestinal diseases. Yellow calcite relieves kidney pain. Calcite beads set in silver help with colds. Lithotherapists suggest that calcite pendants, as well as rings worn on the little finger of the right hand, help with heart disease. Calcite affects the crown chakra. Magical properties Calcite helps its owner to reveal extraordinary abilities – to become clairaudient, clairvoyant, clairvoyant. In order to achieve this, you should meditate with the stone daily from 5 minutes to 12 hours. Experts say that even simply wearing a mineral expands a person’s consciousness, gives him the opportunity to foresee the consequences of new beginnings, new acquaintances, and allows him to comprehend the true attitude of other people towards the owner of the stone. Calcite becomes very attached to its owner, and if a person loses or gives it away, he blocks his magical abilities for a long time and refuses to serve the new owner. Calcite can only be passed on by inheritance. Moreover, the testator must prepare the calcite for the coming change – he must “introduce” the stone to the future owner. This is done using a simple ritual. The owner places the calcite product (or jewelry with it) in the hand of the heir and pronounces the ritual phrase: “I give you away with gratitude for your service. Serve him (name) as you served me” (the phrase is pronounced three times). After this, the new owner of the stone should hold the calcite under running water (to wash away the connection between the stone and the previous owner) and, concentrating on the mineral, establish contact with it. If a person has no desire to reveal his extraordinary abilities, meditation is not needed – the connection will be established after a week of constantly wearing the stone. Astrologers say that calcite can be worn by people born under any zodiac sign except Scorpio. He will refuse to serve the latter, since Scorpios by nature are prone to practicing black magic, and calcite is a magical stone of light forces. Talismans and amulets As a talisman, calcite is an excellent assistant for businessmen, economists, financiers, lawyers and doctors. It makes them far-sighted and protects them from professional mistakes. Astrologers advise car enthusiasts and professional drivers to have calcite products, since it is believed that the stone can protect the owner from the difficulties of the road, in particular from accidents. Application Most often, druses of translucent white, pink, cream, and yellow calcite, which vary in appearance and morphology, are used as decorative collection material. Calcite in druses is often associated with galena, sphalerite, chalcopyrite, fluorite and other minerals. The value of such samples depends on the degree of decorativeness and rarity of all the minerals present. Very impressive are the druses of white and translucent thin-plate, intricately fused calcite crystals, as well as intergrowths of finely leafed papierspar crystals. Such collection material is widespread in calcareous skarns and hydrothermal calcite, including ore-bearing veins. Much less common are scalenohedral and rhombohedral crystals of colorless or yellow transparent calcite-Iceland spar. Colorless, golden-yellow and pink cleavage rhombohedrons of Iceland spar are very popular, allowing one to see the effect of birefringence of light, as well as containing thin mechanical twins with iridescent interference colors or decorative inclusions of white fine-fiber mordenite, bright green celadonite and other minerals. Very original examples of Iceland spar growing on finger-shaped chalcedony secretions. Determined by rhombohedral cleavage, low hardness, violent reaction with hydrochloric acid. source inmoment.ru

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Rocks and minerals used in pietre dure mosaics, as illustrated by a tabletop depicting fruits, flowers and birds

The stone-cutters of the Grand Duke’s Workshop skillfully used the natural variations in color and texture of minerals to show the play of light and shadow, highlight the heterogeneity of the color of fruits, flowers and plants, as well as the rhythmic coloring of representatives of the animal world. At the end of the 80th century, the number of minerals described by Agricola in the middle of the 100th century was limited to 5593–XNUMX species (to date, XNUMX have been discovered), of which not all had properties suitable for stone cutting. And there weren’t enough of them. However, when looking at the mosaic, one gets the impression of a rich variety of materials. Despite the colorful range, a very limited amount of minerals were actually used. One of the key components of the mosaic is calcite. This is calcium carbonate (CaCO3) – the main mineral of limestones and marbles – sedimentary and metamorphic rocks, as well as the “building material” of mollusk shells. In single-crystalline form, calcite was not used in mosaics due to its low hardness (3 on the Mohs scale) and perfect rhombohedral cleavage – the ability of the crystal to split in three directions. However, both limestones and marbles have increased hardness (up to 4), isotropy (uniformity) of stone-cutting qualities and are widespread in Italy, in particular in Tuscany. The background mosaic uses classic black marble (Noir Belge), mined in several regions of Belgium. This material has been known since ancient Roman times; Thanks to its velvety black uniform color and strong shine, it was widely used for the production of pietre dure mosaics in the Medici Workshop. It can be seen in the inlays of the Taj Mahal, in large decorative forms – vases, fireplaces, sculptures, and in floor cladding in various buildings in France (the Palace of Versailles), Belgium and the USA. The vast majority of green and olive leaves, as well as petioles, trees, shrubs and flowers in the peripheral part of the tabletop are carved from local Verde dell’Arno marble. Siena orange-yellow dolomite limestone (Siena Gialo) is used in the edging of decorative elements – hearts and diamonds around the perimeter of the tabletop, as well as in thin ribbons separating the inside from the outside. One of the varieties of marble – marble onyx – has a striped texture and has decorative qualities: it is visible in the image of a snail’s shell and the bodies of some insects. Often, marbles and marbleized limestones contain remains of fossil flora and fauna – similar elements with fossilized coral can be seen in mosaics (antennae of moths). Completely organogenic calcium carbonate – internal fragments of marine gastropod mollusks – is inlaid with many mosaic elements: plumage of parrots and other birds, petals and buds of pomegranate, tulip, and carnation flowers. The characteristic curled structure, moiré colors and luminescence in ultraviolet rays make it possible to determine this with accuracy. The second most common countertop material is quartz. In addition to the coarse-crystalline varieties – amethyst and colorless quartz (rock crystal) and cryptocrystalline – chalcedony and agate, it is the main mineral of jaspers – microcrystalline rocks consisting of quartz and a mixture of clay minerals, giving them color and, thus, a variety of textures. Flint – a natural mineral compound of silica in sedimentary rocks (limestones) – also consists of cryptocrystalline quartz with an admixture of opal – amorphous SiO2; In addition to its strength, flint can exhibit smooth color transitions resulting from impregnation with oxides of various metals and, as a result, the appearance of a diffusion texture called “Liesegang rings.” The color range of jasper consists of white-beige-red, blue-burgundy, green and brown shades. The main advantage of jasper is its fantastic variety of textures, which, when properly selected, create the impression of natural painting. On this tabletop, brecciated jaspers are visible in the white-red petals of the noctule, green-white-brown leaves of Arabian jasmine flowers, brown-red branches of fruit trees, as if “growing” from the corners of the tabletop to the center, in the back of a snake snake, orange-green dried orange, purple-burgundy fig. Sicilian orange-red jasper Diaspro di Sicilia was taken to inlay the pomegranate fruit, receptacle and sepals of pomegranate flowers. Patterned jasper in orange-brown tones is used for the leaves of morning glory flowers. To the naked eye, this jasper is almost indistinguishable from marble leaves of a plum tree – the natural pattern of the stone is so skillfully selected. The striped abdomen and chest of insects – some flies, wasps, moths, as well as the wings of locusts and the bodies of caterpillars are made of striped jasper and agates. Thin-striped, weightless wings of moths, flies and butterflies are made of gray-white, sometimes with red flashes, agates. The bright red, spotted fruits of the male dogwood and orange hawthorn asarol appear to be carved from Sabina agate. White with yellowish, pinkish and grayish shades are the petals of jasmine, cherry, hibiscus, dogwood, narcissus, tulip, rose hip, orange, carnation, hyacinth, honeysuckle, as well as yellow-orange fruits of cherry, plum, apple, pear, lemon, quince, peach are made mainly from Volterra chalcedony (Calcedon di Volterra) – an area famous for the extraction of snow-white gypsum-alabaster. Transparent, yellow-orange varieties of chalcedony – carnelian represent the juicy fruits of the cherry, the flower of the curly lily, and the wings of the hoverfly. To add color to pale-colored transparent materials and enhance their internal reflection, metal foil was placed underneath them when making mosaics. This countertop is no exception: foil covers the back of chalcedony cherry berries and amethyst quartz drain. Often, to enhance the intensity of the color, the foil was tinted: where the paint has disappeared over time, it is clear that the purple plum has acquired the color of natural amethyst, in which the growth zones of colorless rock crystal are replaced by zones of purple amethyst. For plum fruits and grapes, a block aggregate of amethyst and fragments of geodes were used, which can be easily read by the direction of growth and orientation of quartz crystals. Quartz is one of the hardest materials selected for this countertop. It is impossible not to note the high skill of the craftsmen who processed such a difficult material: it is hard, crumbles noticeably, but, nevertheless, the edges of the fruit are processed perfectly and fit into one another with minimal gaps. Quartz also partially fills the volume of greenstone jaspers, the so-called Diaspro di Barga, heterogeneous in both color and texture, which line the leaves of hibiscus and bindweed flowers in the central part of the tabletop. Probably, the term Barga includes both jasper itself and other hard rocks (pietre dure) of green color. These rocks are heterogeneous in texture, in which fibrous and scaly aggregates of complex silicate minerals – amphiboles, serpentines, mica – are located in spots, blocks and stripes, “impregnated” with quartz. Based on its mineral composition and inherited texture, this rock can be classified as listvenite. The bright, emerald green material was apparently rare. It is encrusted with several fruits of unripe almonds and some sections of stems – multicolored jasmine and pink carnations. Like the previous material, it has a mottled texture – from white to grassy green. This is the so-called smaragdite – an emerald green actinolite mineral. The word “smaragdite” comes from the ancient Greek Σμάραγδος and means “green mineral”. This dense aggregate of green actinolite with snow-white spots is classified as jade. Jade is an extremely tough mineral that has exceptional strength but is difficult to process. In addition, natural manifestations of smaragdite are extremely rare; it could have been an accidental find at any asbestos deposit. However, there are often cases of import of rare minerals from other countries. One of the most striking examples of such material imported to Europe is Persian bright blue lapis lazuli. Mining of lapis lazuli has been known in Afghanistan (Badakhshan province, Sar-e-Sang deposit) since the 4th century BC. Since the 5rd century BC. lapis lazuli was transported along the Great Silk Road, that part of it called the “Lapis Lazuli Road” – from the foothills of the Pamirs to the countries of the Middle East and further to the west. This gem was exotic in Europe: nothing similar in color was found here. The extraction of the stone took place at an altitude of XNUMX–XNUMX thousand meters above sea level, transportation took a long time, so it is not surprising that this rare gem, as well as the source of raw materials for blue mineral paint, was worth its weight in gold. It is believed that the highest quality lapis lazuli is a uniform dark blue color, with almost no inclusions of other minerals. Such fragments are visible along the edges of the tabletop – in geometric patterns with hearts and rhombuses. Typical inclusions in this lapis lazuli are bright yellow crystals of pyrite with a metallic sheen, which is often confused with gold. On the semantic part of the tabletop, blue flowers (morning glory, hyacinth, cornflower) and part of the plumage of birds (common blue tit, blue-red lory, blue jay and cardinal) are inlaid with heterogeneous pale blue lapis lazuli. Upon closer examination, it turned out that lapis lazuli is in association with whitish sodalite and calcite and also contains small inclusions of pyrite crystals. The use of such heterogeneous lapis lazuli emphasizes the natural three-dimensional forms of flowers and birds and creates the illusion of wind. The bluish-gray flowers of bindweed with random streaks are of interest due to their unusual coloring and the fact that they are rarely found in products similar to the item under study. No samples were taken due to completed restoration work, and the available arsenal of research methods only allows us to narrow the range of suspected materials. The color and flowing texture of the stone suggests a non-crystalline and possibly man-made material, such as glass or obsidian. However, the rarity of its use in the products of the Grand Duke’s Workshop suggests that this is a piece material, which cannot be said about glass. Similar material is also known in nature – flint from the Arno River valley – Selce dell’Arno; color stains are precisely characteristic of diffusion impregnation of flints, and the bluish-gray color is also known in other manifestations of minerals, however, the shades of the color palette do not quite correspond to the material of bindweed flowers. Finally, the color and structure reveal bluish-gray minerals with a greenish overcolor of the alkaline amphibole group, “impregnated” with quartz—riebeckite, arfvedsonite. Note that not far from Florence, in the province of Grosseto (Monte Argentario commune), an ancient manifestation of riebeckite, which is called “blue marble,” is known. However, quartz impregnation of this material makes it possible to determine in situ only silica, which corresponds to flint, chalcedony, and glass. The dominant feature of the composition is the slightly open pomegranate fruit with smooth dark red grains of the mineral of the same name peeking out from under the peel. The garnet group includes more than 15 mineral species, and the most common one was used here – almandine Fe3 2 +Al2[SiO4]3. It is widespread in metamorphic rocks and forms fairly large and transparent crystals ranging from dark red to cherry purple. Almandine is described in the works of Agricola and was known even under Pliny the Elder as the “carbuncle of Alabandia.” Ten crystals of transparent almandine in pink, red-violet, crimson, orange-red and intermediate shades with a backing of gold and silver (?) foil, create a feeling of volume and inner glow of ripe pomegranate grains.

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