Rare and valuable minerals

What is the difference between carnelian and chalcedony?

CARNELIK [< gr. sardonyx sardonyx] - a mineral, a variety of chalcedony and agate, brown-red or with alternating stripes of white and brown-red.
CHALcedony [gr. chalkedSn] – mineral, cryptocrystalline variety of fibrous quartz; usually found in the form of spherical, grape-shaped, kidney-shaped formations, in the form of veins, etc.; There are varieties: red x. (carnelian), green (chrysoprase, heliotrope), brown (sarder), STRIPED (agate, onyx, CARNELIUM), etc.; semiprecious stone.
The mineral carnelian is chalcedony (species), but not all chalcedony is carnelian. Other answers Carnelian (from the Old Russian “shape like a heart”) is the collective name for chalcedony (a cryptocrystalline variety of silicon dioxide), sarder (from Sardis – the name of the capital of the Lydian kingdom, located near the Aegean coast of modern Turkey), carnelian (from lat. cornum – dogwood), lincurium. Carnelian, sarder, carnelian are among the few names of precious stones that have come down to us through millennia practically unchanged. The oldest now obsolete synonyms for the name “carnelian” were “akik”, “wakler” and “demion”. Consists of a cryptocrystalline variety of silicon dioxide, naturally colored by hydroxides and iron oxides in chestnut, brown-red (sarder); red, orange-red (carnelian); orange-yellow and yellow (linkurium) shades. Carnelian hardness is 6,5-7, density is 2,6 g/cm3, degree of transparency is translucent to transparent. Carnelian was formed by ancient volcanic processes in the bubbles (almonds) of lava flows and volcanic vents, where it occurs along with agate and other colored varieties of chalcedony. But, as many geologists believe, it acquires its rich color already on the surface, after the destruction of the volcanic rocks bearing it, including under the influence of sunlight. The location of the best carnelians in Russia is Eastern Siberia: the Zeya River basin (Amur region), Yakutia, Chukotka, Buryatia, southeast of the Chita region; Of the foreign deposits, it is probably worth mentioning India (Deccan Plateau, Gujarat), Mongolia, USA (Montana), Fr. Madagascar, Uruguay and Brazil. The first products made of carnelian (the most ancient tools) were found during excavations of sites of Paleolithic man (800-60 thousand years ago). years BC e.) . Carnelian has been used as a material for the manufacture of jewelry, amulets, talismans and religious objects since the early Neolithic period (18 thousand BC). years BC e.) . This wonderful stone was most popular in Ancient Greece, Mesopotamia, the Middle East, Rus’ and medieval Europe. It was valued significantly higher than many precious stones and metals known at that time, for example, in the 4th century AD. э. carnelian took fifth place in value in the row: diamond, pearl, emerald, noble opal, carnelian, red carbuncles (spinel, ruby, garnet) and then gold, silver, sapphire and topaz. Amulets, rings, other jewelry, carved seals, cameos, intaglios, figurines, cups, and crosses were made from it. Carnelian is a traditional material for making jewelry. Carnelian in general was loved by many great and famous people: history included pendants and the favorite carnelian vessel with eye shadow of Queen Cleopatra (69-30 AD). BC. BC), a belt buckle decorated with carnelian “Shaker of the Universe” warrior Tamerlane, the seal of the last hetman of Ukraine Kirill Razumovsky, Byron’s talisman ring, according to legend given to him in Greece by the gypsy Hataje (in fact, it was presented to the poet by his friend Edleston, allegedly as a token of gratitude for saving his life). In Ancient Egypt, carnelian was likened to “the sunset frozen in stone,” and was considered the stone of the goddess Isis (the mother of all gods), capable of bringing wealth and glory, ensuring a calm descent into the afterlife and a sweet stay in it. According to J. Kuntz, the 156th chapter of the Egyptian “Book of the Dead” begins with these words: “The chapter is about a buckle made of carnelian, placed on the neck of the deceased. The blood of Isis, the virtue of Isis, the magical power of Isis, the magical power of the Eye guarding this Great (deceased) – they will ward off any evil that threatens him.” It is apparently no coincidence that carnelian products, including images of the sacred scarab beetle, are constantly found in ancient Egyptian burials. On the mummy of Pharaoh Tutankhamun (XIV century BC) э. The many-sided and varied chalcedony hides under a whole list of names. The translucent texture, fantasy designs and delicate tonality of natural shades have made it one of the most popular jewelry and semi-precious stones.

Composition and origin

Chalcedony has the same composition as the well-known quartz SiO2 (silica), but a cryptocrystalline fine-fiber structure. Fiber-crystals twist and grow together, forming crusts and massive fractions, often with a banded and concentrically zoned structure. Fibrous quartz is formed in cavities, cracks, geodes of volcanic and o cage rocks, covering their walls. Perpendicular fibers grow on the lining layer, which always stretch towards the center of the empty area. When the process fades, large quartz crystals can grow in the middle of the cavity, forming druses. The liquid from which the mineral crystallizes contains impurities that color it in different colors: green (chrome), red (iron), pink (manganese).

Varieties of chalcedony

  • Carnelian is a translucent chalcedony with a predominance of yellowish-red shades due to impurities of oxide or ferrous iron.
  • Chrysoprase has a green color with a bluish tint and is formed in the presence of impurities of nickel-containing silicates.
  • Agate is a glossy milky white, gray, bluish chalcedony with a concentric structure, often containing inclusions of opal and crystalline quartz.
  • “Moss agate” (moss, dendritic agate) – differs from ordinary agate in that against the background of stripes and concentric circles, inclusions of manganese or iron oxides stand out effectively, forming subtle intricate patterns.
  • Onyx – has a parallel-layered structure; along with chalcedony itself, the layers can be formed by crystalline quartz, jasper, opal (an opaque amorphous type of silica).

It is the arrangement of the stripes and the shine that distinguishes onyx from agate. Straight parallel stripes and a matte sheen for onyx and concentric circles with a more glossy sheen for agate.

The process of chalcedony formation takes thousands and even millions of years. During this time, the composition of the environment, temperature, and pressure change. And the more often they change, the more interesting the appearance of chalcedony.

Known deposits

Chalcedony is a fairly widespread mineral, mined in different parts of the world. The most famous deposits are in Brazil, Madagascar (rare blue, pink, green translucent stone), Mexico (fire agate), Scotland, USA, Germany, Czech Republic, Poland, Turkey, Tanzania, Australia.

Russia has many deposits in Transbaikalia, Eastern Siberia, the Amur region, the Far East, and also in Crimea. High-quality ornamental and jewelry stones are extracted from them: onyx, translucent agates, carnelian and carnelian (deep red chalcedony).

Popular chalcedony products

Chalcedony has been used for making jewelry and decorative items since ancient times. It is used to make beads, cabochons, ring inserts, earrings, pendants, necklaces, and cufflinks. The nobility of this stone, smoky shades, and subtle patterns can turn each of them into a unique, inimitable thing.

Striped onyx is used for artistic carving; sculptures, figurines, and bas-reliefs are created from it. Vases, book stands, writing accessories, mirror frames, and paintings made from different types of chalcedony are also highly valued. Mosaics and tiles made from this stone decorate luxurious fireplaces, bathrooms and dining rooms.

Refinement of chalcedony

Like many jewelry stones, chalcedony undergoes refinement. But in this case, the main method of refining chalcedony is dyeing.

There are a huge variety of techniques, from exposure to acids and temperatures to impregnation with dyes based on various metals. Perhaps the most popular example of such an effect is the famous black agate (onyx).

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