Yingshi high-quality jade quartzite jade

I. Overview

Timing is a mineral widely distributed in nature, which can be produced in the form of single crystal and aggregate, and the aggregate form can be divided into crystal and aphanitic.

The definition of jade in this book is: jade in time is a polycrystalline aggregate with small mineral components such as jade.

In this definition, it is emphasized that timely jade is formed by geological process (that is, naturally formed), which means that the color, structure and structure are kept in a natural state, which is different from timely jade after artificial treatment; Secondly, it is emphasized that a few minerals such as timely jade are polycrystalline aggregates, and it is pointed out that the main mineral of timely jade is timely, and there are some other minor minerals such as chromite, which are different from other jade on the one hand and crystal on the other. Finally, it is emphasized that reaching the jade level means that it must have a natural polycrystalline aggregate with strong luster, beautiful color and delicate texture, which is different from ordinary quartzite.

Second, cryptocrystalline British jade.

Cryptspar British jadeite mainly includes chalcedony and agate.

(a) chalcedony (chalcedony) and jasper (jasper)

1. Overview

Cryptomere is called chalcedony, and unlike agate, it has no banded structure. Jasper is a mixed mineral impurity of chalcedony, such as clay. Even if there is a banded structure, it is not called agate, but "banded jasper". Other characteristics of chalcedony and jasper are similar to agate.

2. Varieties of chalcedony

Because chalcedony has various beautiful colors and is also the raw material of important handicrafts, it is divided into the following varieties according to colors.

Chrysotile: Apple green or light green, blue-green, because it contains NiO. The texture is fine, dense and massive, and no granular structure can be seen by naked eyes. The glass is shiny and the shell is broken. Slightly transparent-opaque, green looks like jade. High-quality products are produced in Australia, so they are called "Australian jade". The goods marked as "Australian jade" in the market are not necessarily chrysotile imported from Australia. Yellow and green jade is also called "yellow and green jade".

Praseodymium: It's green, and some of it is green because of chlorite. Most of them are translucent and opaque, and the dark ones are also called "dark green chalcedony".

Chalcedony: Chalcedony is reddish to rich red, and some are brownish red because it contains Fe2O3. Brazil, India and Japan are the most famous foreign producing areas. China, Gansu, Ningxia and other places also have a small amount of output.

Blue chalcedony: different shades of blue opaque to translucent chalcedony. Blue minerals are the main cause of color. The main variety is chrysocolla-colored chrysocolla chalcedony, which is produced in the United States and Taiwan Province Province of China.

White chalcedony: slightly transparent to translucent white chalcedony. Colorless and translucent people can dye chalcedony in various colors, while people with gray or impure colors are difficult to use in jewelry industry.

Bloodstone: It is a dark green opaque-slightly transparent jasper with reddish-brown spots on it, just like dripping blood, hence the name Bloodstone. Its most famous place of origin is India.

Jasper: chalcedony containing mineral impurities such as clay. According to color, it can be divided into green jasper, red jasper and yellow-brown jasper, but green jasper is more common. Egypt is rich in yellow-brown jasper, which is called Egyptian jasper because it contains iron oxide. Those with clay minerals and wide bands are called banded jasper. A patterned jasper produced in Oregon, USA, is called "landscape jasper". Landscape jasper is a kind of colorful jasper, and different colors complement each other, just like a beautiful natural landscape painting, hence the name.

identify

Agate is easily distinguished from chalcedony or jasper because of its banded structure. However, some small products such as chalcedony and jasper are easily mixed with products such as Dongling stone and dense jade, and can be distinguished according to the differences in color and texture. For example, Dongling stone or dense jade products are brighter than chalcedony products, and the texture is not fine enough because their particles are coarse; Chrysotile is very similar to jadeite, turquoise or Tianhe stone. The difference is that green jadeite has a staggered structure of variegated crystals, and variegated crystals and fibrous jadeite crystals can be seen; Turquoise has poor transparency, porcelain has low luster and hardness (5 ~ 6); Tianhe stone has obvious plaid stripes.

4. The economic evaluation basis of chalcedony and jasper

The evaluation of chalcedony and jasper is mainly based on their color, texture and fragmentation. In the glass floor, green chalcedony is the most precious. For example, "Australian jade" has the reputation of "old pit jade characteristics", and the greater the fragmentation, the better. Chlorite is generally small in size.

5. Genesis of chalcedony and jasper deposits

World-class chrysotile asbestos is produced in Rockhampshire, Queensland, Australia. Chlorite exists in veins of lateritic silicified serpentine and laterite. There are two views on the reasons. One view is that chrysotile is a siliceous metasomatism of ultrabasic rocks after serpentinization, and nickel-containing chrysotile is formed in the structural fracture zone, and then weathered out of the surface by the surface weathering crust, and its essence should belong to the post-volcanic hydrothermal origin. Another view is that SiO2 _ 2 and Ni _ 2+precipitated from silicified serpentine during laterization are deposited in the structural fracture zone with surface water. Many countries in the world produce chalcedony, but high-quality chrysotile is only found in Australia, Sri Lanka and India.

(2) Agate

Agate is chalcedony with different color stripe structure. Agate, the English name of agate, is the Latin name of charters River in Sicily. Agate was first discovered in Italy.

Agate is a popular intermediate jade material since ancient times. According to research, human beings have used agate for more than 5000 years. During 1970, Xi 'an hejia village discovered two treasures hoarded by digging and burning bricks in the Tang Dynasty. Among them, there is a "tauren cup" carved with agate, which is very exquisite in craftsmanship. It can be seen that agate carving reached a quite high level in the Tang Dynasty more than 1000 years ago. Now, agate products are one of the main products exported by China gemstone industry.

1. Mineral composition and chemical composition

Agate is mainly composed of chalcedony, sometimes containing a small amount of opal and microcrystal. The chemical composition is mainly silicon dioxide, but also contains a small amount of trace impurities such as iron oxide, magnesium oxide, calcium oxide, nickel oxide and manganese oxide.

2. Morphology and physical properties

Description: banded aphanitic block. The shape is often kidney-shaped, bell-shaped, grape-shaped and shell-shaped.

Color: Agate is white, but due to the existence of colloidal particles and other impurities, it often appears gray, brown, red, blue, green, green, pink and black, and sometimes it forms beautiful stripes because of color mixing. The red stripes contain iron oxide, carbon black, white magnesium oxide, calcium oxide, green nickel oxide and brown manganese oxide.

Other physical properties: glass luster, translucent. Shell fracture. Hardness 7. The density is 2.61~ 2.65g/cm3. The refractive index is 1.54 ~ 1.55.

Step 3 diversify

Common agates are as follows.

Onyx: Agate with ivory or white stripes and black or dark brown stripes. The strip is relatively straight and uniform. It is an ideal material for making relief. The black part is used as the background, and the white part is used to carve patterns.

Moss agate (Mocha agate) refers to light blue, gray or yellow translucent chalcedony containing dendritic inclusions. Most of these ferns and mossy inclusions are various oxides, but some of them are composed of tiny scales of chlorite and amphibole. Dendritic inclusions make agate have beautiful appearance and great technical value. Agate with fine moss is a very precious variety in chalcedony materials. Mocha is the origin of Yemen's high-quality agate, so agate is sometimes called mocha stone.

Agate: Agate made of translucent thin chalcedony and iron mineral crystals sandwiched between layers. Because the flaky crystals of iron-containing minerals can present a beautiful red rainbow color, it is called agate.

Blue agate: Natural blue agate is produced in Brazil, and the same blue and white bands have very clear boundaries. People often use this completely different layer ribbon as relief.

Aris agate: Agate with spectral color. This is the diffraction effect caused by twisting the optical fiber. This color looks best when the material is sliced and placed under a light source.

Water bile agate (): The agate with closed cavity water is called water bile agate.

identify

According to the unique banded structure of agate, it is easy to distinguish it from other jade.

5. The basis of agate economic evaluation

Agate is graded according to color, transparency and blockiness. Apart from the most precious materials in water bile agate, it is generally the best for two colors to be matched with harmonious and pretty materials. China divided agate into four grades. Supergrade, Grade I and Grade II are characterized by red, blue, purple and pink, transparent, without impurities, sand cores and cracks, and the differences are between 4.5kg, 1.5kg and 0.5 ~ 1.5kg respectively. The third grade is red with variegated color, brownish yellow, light purple, transparent and slightly cracked, and the block weight is below 0.5kg. Generally speaking, the price of super grade material is 3.5 times that of the third grade material.

6. Genesis of agate deposit

Agate is mainly a hydrothermal deposit after the basic volcanic period, that is, the hot water solution left after the eruption of basic volcanic rocks accounts for the basic rocks erupted in the early stage, and the precipitated SiO2 _ 2 precipitates in the pores and holes of basic volcanic rocks, forming a ring agate. It also exists in sedimentary and gravel layers and in the accumulation layers of modern residual slopes. Agate is famous in India, Brazil, the former Soviet Union, Ireland, the United States, Uruguay, Egypt, Australia, Madagascar, Mexico and Namibia. Agate is widely distributed in China, including Heilongjiang, Liaoning, Inner Mongolia, Hebei, Ningxia, Tibet, Hubei, Shandong and other places. Nanjing Yuhuatai produces famous pebbles, mainly agate and a small amount of chalcedony, which is called Shi Yuhua.

Third, Jing Shi Ying Yu

Crystal seasonal jade includes silicified asbestos, silicified wood and quartzite jade.

(a) Silicified asbestos (silicified crocidolite)

1. Overview

Asbestos silicide is an aggregate composed of timely and metasomatic alkaline amphibole residues, which reaches the jade level in geological process. Because its appearance has a brownish yellow tone, and it is spun silk luster and imitates wood, it is also called wood to stone in some literatures. Because of its parallel fiber structure, we can often ponder the opal effect. Because of its quaint beauty, it is deeply loved by people. According to written records, China was decorated as early as the Yuan Dynasty.

2. Mineral composition

The main mineral components of silicified asbestos are alkaline amphibole and a large number of fine particles. In some literatures, alkali amphibole is represented by sodium amphibole. The amphibole in silicified asbestos (tiger's eye stone) produced in Xichuan County, Henan Province has been confirmed as magnesium sodium amphibole (Liu et al., 1993).

3. Morphology and physical properties

Description: It is usually massive and has fibrous structure.

Color: Brown, brown, green, blue, cyan gray, blue gray, and some are purple.

Other physical properties: silk luster. The hardness is 6 ~ 7, the density is 2.9 ~ 3.3g/cm3, and it has toughness.

According to electron probe microanalysis, most fibrous magnesite amphibole has been silicified, and the content of silica is about 70%, which is the illusion that aphanitic silica is fibrous magnesite amphibole.

Step 4 diversify

According to the color characteristics, silicified asbestos can be divided into tiger eye stone, eagle eye stone and zebra tiger eye stone.

Tiger eye: the silicified asbestos is fully oxidized, so the tiger eye appears as a series of yellow and brown flashing bands, and the positions are exchanged when rotating. Proper cutting and grinding will show the cat's eye effect, but the eyeliner is not good. Those with cat's eye effect due to curved surface, like "tiger's eye stone", are called tiger's eye stones.

Hawkeye: A person who grinds blue, blue-green and blue silicified asbestos into an arc and has the cat's eye effect of "Hawkeye" is called Hawkeye.

Zebra Tiger Eye: Brown and blue silicified asbestos is polished into a curved surface with cat's eye effect, which is called zebra tiger eye.

identify

Special yellow and blue, obvious fine fiber structure, bright silk luster, it is easy to distinguish from other gems. Hardness and density are lower than emerald, which is different from emerald's cat's eye. In addition, the light bands of tiger's eye stone, eagle's eye stone and zebra's tiger's eye stone are loose, the brightness is not strong enough, and the texture is not enough water, which is also an important difference from jade opal stone.

6. Basis of economic evaluation of silicified asbestos

It is required that the raw materials of silicified asbestos are dense and have strong silk luster, which is generally divided into three grades.

First-class products: beautiful silk pattern, alternating with Huang Honglan, dense texture, no cavities and impurities, with the number of blocks above 10kg.

Second-class product: general pattern, alternating yellow, red and blue, dense texture, with a few holes and a few impurities, and the weight of the block is above 5kg.

Third-class product: Huang Honglan with no pattern, dense texture, a little void and impurities, and the weight of the block is more than 2kg.

7. Genesis of silicified asbestos deposit

The largest silicified crocidolite deposit in the world is located in transvaal province (azania). The main ore bodies are related to crocidolite. The crocidolite layer and silicified crocidolite are integrated in Precambrian extremely fine iron-bearing sandstone. The mineralization zone is 10m thick and consists of many intermittent parallel silicified crocidolite veins. Silicified crocidolite is a kind of seasonal jade, which is silicified from crocidolite. Except South Africa, the main producing areas are Brazil, India and Sri Lanka. At present, the only known origin of silicified asbestos in China is Xichuan.

(2) Silicified wood

1. Overview

Silicified wood is a kind of jade that retains the appearance of wooden structure after buried trees replace the silicon dioxide contained in groundwater.

2. Mineral composition and chemical composition

The main minerals are agate, opal or aphanitic. Its chemical composition is basically silicon dioxide, which often contains metal impurities such as iron.

3. Morphology and physical properties

Description: Most of them are tree-shaped opaque blocks, with wood structure preserved.

Color: Brown, light yellow, tan, gray and gray.

Other physical properties: specimens are often dull, glassy and opaque after polishing. Hardness 7. The density is 2.65 ~ 2.95g/cm3. The refractive index depends on different kinds of silica, such as agate, timely or opal.

Step 4 diversify

According to different varieties of silica, it can be divided into opal silicified wood, agate silicified wood and ordinary silicified wood.

Opal silicified wood: it is called opal silicified wood with opal minerals as the main component.

Agate silicified wood: wood mainly made of agate is called agate silicified wood.

Silicified wood: called ordinary silicified wood, it is mainly composed of cryptocrystalline materials.

identify

It is distinguished from other kinds of jade by its obvious wooden structure.

6. Basis of economic evaluation of silicified wood

Those with clear wood structure and strong luster can be used as raw materials for carving, while those with large wood structure can be used as furnishings or treasures, and can also be used to decorate gardens.

7. Genesis of silicified wood deposit

It appears in the strata with wood fossils. The main producing areas are European countries and the United States and other countries. China, Hebei and Liaoning provinces also have output.

(3) Quartzite jade

1. Overview

Quartzite jade is a kind of aggregate mainly composed of fine grains, which reaches the level of jade in geological process. Some colors are beautiful because they contain colored minerals.

2. Mineral composition and chemical composition

The main mineral is fine grain strain, and different varieties may contain a small amount of colored minerals such as chromite, manganite, lepidolite and actinolite. The main chemical composition is silicon dioxide, which contains a small amount of other impurities.

3. Morphology and physical properties

Morphology: Most of them are dense blocks.

Color: it can be white, blue, green and purple.

Other physical properties: mostly glassy, opaque to almost transparent. The hardness is 6.5 ~ 7. The density is about 2.65g/cm3.

Step 4 diversify

(1) Dongling Stone, also known as Dongling Shi Ying, refers to quartzite with placer effect because it contains a lot of flaky mica or iron ore. The placer gold effect refers to the scintillation effect caused by the reflection of light by iron mineral fragments such as hematite or mica and copper sheets contained in gem materials. Granular structure, coarse particles, obviously visible green chromite mica scales or fibrous or granular blue-green or cyan manganese ore. Now some quartzites containing actinolite in China and Xinjiang are also called Dongling Stone. It can be divided into many varieties by color (containing colored minerals). Quartzite containing blue-middle-manganese-aluminum garnet is called "Landong Lingshi"; If chromite is emerald green, it is called "green Dongling stone"; If lepidolite is purple, it is called "Zidonglingshi".

(2) Miyu: It is a kind of green dense massive chromite mica quartzite, which is called "Mixian Jade" for short because it is produced in Mi County, Henan Province. Jadeite is mainly composed of 95% ~ 99% quartz with a grain size of 0.03 ~ 0.6 mm, and also contains 1% ~ 5% chromic muscovite and a small amount of minerals such as zircon, rutile and apatite. Oily luster, opaque to almost transparent. Hardness 7. The density is about 2.65g/cm3. Due to the different content of chromium-containing muscovite, dense jade presents different colors of white, light green to green, and dark green is the best. Because the secret jade is mostly light-colored, it is often improved by dyeing. Jade is intermittently distributed in the gray fine-grained quartzite of Maanshan Formation in Sinian system in the form of veins and lentils.

(3) Golden white jade: it is a kind of white dense massive quartzite, named after it is produced in Xishan, Beijing. After polishing, the jade carved with it is very similar to Hetian jade's most precious variety "sheep fat jade", but it is brittle but not tough; Under the magnifying glass, the fiber interwoven structure without the characteristics of suet jade is granular structure. Jade is produced in Sinian sedimentary strata in Mentougou mountain area of Beijing.

(4) Guizhou jade: It is a fine-grained quartzite containing kaolinite minerals. It is named because it is produced in Qinglong County, Guizhou Province, and it is grayish green and light green. The main mineral is Yingshi, with a particle size of 0.05 ~ 0. 1.5 mm and a small amount of kaolinite. Because of the uneven distribution of green kaolinite, the texture is fine. In a band structure. Guicui is emerald green, light green, gray green and red. This kind of glass is glossy and opaque, with a hardness of 7 and a density of about 2.65g/cm3.

identify

Quartzite jade is metamorphic quartzite with grain mosaic structure, which can be distinguished from white jade, jadeite and serpentine jade. The refractive index of quartzite jade is close to 1.54, and its density is about 2.65g/cm3, which is lower than jadeite, nephrite, prehnite and garnet.

6. Basis of economic evaluation of quartzite jade

Quartzite jade in China is divided into three grades according to color, texture and fragmentation.

Grade I: green, light green and white, fine texture, good transparency, no impurities, and the weight of the block is above 7kg.

Grade II: Beans are green or white, with bright color, fine texture, good transparency and no impurities, weighing more than 5 kg.

Grade III: light green, white or brownish red, without cracks, containing a small amount of impurities, with a block weight of over 5kg.

Generally, the price of first-class products is three times that of third-class products.

7. Genesis of quartzite jade deposit

Quartzite jade occurs in sedimentary strata containing quartzite, and most of them belong to late hydrothermal metasomatic deposits. The main producing areas are Spain, India, the former Soviet Union and Chile. China is produced in Mi County of Henan Province, Qinglong County of Guizhou Province and Mentougou District of Beijing.

Fourth, the optimization and identification of seasonal jade.

There are two main methods to optimize the seasonal jadeite: heat treatment and dyeing treatment, and water injection treatment in water bile agate.

1. heat treatment

In addition to trivalent iron, there are some gray ferrous iron in many red agates or gray agates with incorrect hue. If agate containing bivalent iron is heated and oxidized to trivalent iron, the color of agate will turn red. The color of the baked agate is relatively uniform, and the edges of the color are gradually changing, which is not as clear as natural red agate. Baked agate is no different from natural agate in nature, its color will not change, and its value is similar to that of natural agate.

The tawny tiger's eye stone can be transformed into brownish red by heat treatment under oxidizing conditions. The tiger's eye stone can be turned into grayish yellow and grayish white by heat treatment under reducing conditions, which is used to imitate the golden emerald cat's eye.

2. Dyeing treatment

Most agate products on the market are dyed. Colorless agate (with different formulations) can be dyed with inorganic dyes to the required color. Agate is soaked in iron nitrate solution, then heated, dyed and boiled, which will produce red color. Soak agate in saturated ferric chloride and heat it slightly to produce lemon yellow. Agate turns green after soaking in saturated chromium salt solution and heating; After soaking in nickel nitrate and heating, the dyeing effect is similar. Soaking agate in potassium ferrocyanide solution, then soaking it in ferric sulfate solution and boiling it will produce blue color. After agate is soaked in sugar solution, heating or adding nitric acid will dye agate brown. Firstly, the agate is soaked in concentrated sugar, and then it is taken out and immersed in hot concentrated sulfuric acid. Sugar carbonizes and turns black. The dyed agate is bright and uniform, giving people a false feeling.

Dyeing treatment of quartzite only appeared in recent ten years. It is made of quartzite by heating and quenching before dyeing. It is mainly dyed green and used to imitate jadeite. Commonly known as Malaysian jade in the market.

3. Water bile agate water injection treatment

When cracks appear in water bile agate or during processing, the water in the water bag will slowly overflow and dry up, making water bile agate lose its technological value. The treatment method is to immerse it in water and backfill the water by capillary action, or backfill the water by injection, and then seal the gap with glue. The identification method is to carefully look for whether there is a seal crack.

Seasonal jade is a large number of middle and low grade gems, and its optimization treatment has a long history. For example, the heat treatment and dyeing treatment of agate have been accepted by people, so it is not necessary to indicate it when identifying it. However, it must be pointed out that some varieties of timely jade are optimized and used to imitate other high-grade gems. For example, quartzite dyeing is named after "Ma Laiyu" and used to imitate jadeite; Tiger's eye stone is used to imitate the golden emerald cat's eye after fading.

Think about a problem

First of all, is it right or wrong?

1. The goods marked "Australian jade" on the market are chrysotile asbestos imported from Australia.

2. The effect of dyed agate is stable, and it doesn't need to be marked and treated when it goes on the market.

Second, multiple choice questions

1. Jasper is:

A. aphanitic time

B. agate without banded structure

Chalcedony mixed with mineral impurities such as clay

2. However, high-quality chrysotile exists only in:

A. Australia

B. Sri Lanka