Myths and legends

What is the difference between chalcedony and carnelian?

No. 1. 4-305. Carnelians CIS

Formula: SiO2
Application: jewelry and semi-precious stone
Variety: chalcedony
Investment name: Carnelian (a group of varieties of chalcedony)

Features

Hardness (Mohs Scale) 6,5-7,0
Density 2,57-2,64
Refraction 1,530-1,539
Birefringence 0,006
Variance No
Color Orange, pinkish, reddish, yellow, red-orange.
Transparency Cloudy, translucent.
Forms of selection Fibrous, cryptocrystalline veins, crusts, sinter aggregates, nodules.
Syngonia Triclinic.
Cleavage Absent.
Kink Irregular, less often shelly.
double refraction White.
Pleochroism Absent.
Absorption spectrum lines Not interpreted.
Luminescence and Chelsea filter Absent.
Characteristics Stands out as an orange variety of chalcedony. The redder chalcedony stands out as carnelian, the browner one as sard or sarder, the yellower one is called lincurium. The transition boundary is conditional. Banded chalcedony is distinguished as agate.
Field Russia (Crimea, Khabarovsk Territory, Buryatia, Transbaikalia), India, Brazil, Uruguay.
Brilliance Glass.
fragility Viscous.

More about carnelian

CARNELIK – a variety of CHALcedony Carnelian is a translucent to translucent variety of chalcedony (cryptocrystalline quartz), distinguished by color: from yellow-orange and orange to orange-red. Abroad, carnelian is known as Carnellian. Another, also Russian trade term, referring to chalcedony of essentially the same color is carnelian. The best carnelian stones are orange-red translucent stones. Carnelian is very popular in Russia, and since ancient times, when it was processed with baroque cutting (tumbling). Cabochons are made from carnelian. Inexpensive but beautiful jewelry is usually made from silver or base metals. Carnelian is very often used in the manufacture of small figurines and other small shapes. Carnelian is refined – sometimes the color of the material can be improved by cutting it into plates and heating it on a gas stove in a tin can lined with asbestos on the inside. First, a small flame is maintained for about 1 hour in order to remove all water from the material, then the flame is increased and the stones are heated to a high temperature. Cooling should be gradual.

Market prices* for inserts, raw materials and collection stones (in USD) (*indicative)

Faceted inserts (per 1 carat) Gold price ratio
1 carat or less 3-5 carats 10 carats or more
In Russia 0,5 – 3 ($0,5 – 3 per cable) 0,1 – 2 ($2 – 10 per cable) 0,05 – 1 ($5 – 20 per cable) 0,01 – 0,3
Abroad see Carnelian see Carnelian see Carnelian see Carnelian
For 1 g of raw materials Crystals Shufts Rarely available for sale
In Russia 3,5 – (10) – 20 $/kg 1 – 100 (current ag.) not presented in specimens widely spread
Abroad see Carnelian see Carnelian see Carnelian the term is not used

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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