They are in the form of plates, sheets, grapes, kidneys, radial or massive aggregates. A good quality grape stone can be used as a gemstone. This gem is known as the Cape of Good Hope emerald.
Introduction to minerals:
English name: prehnite
Grape stone mineral (rock) name: grape stone. Produced in Sichuan Province, Zhangzhou, Leshan and other places. The stone color is mostly green, and there are a number of raised color blocks on the stone surface, which are like grapes, hence the name. The grape stone is mellow and smooth, crystal clear and lovely. It is better to have a contrast between the particles and the base color, and the grain is large and round, and it is also embossed to form a graphic. Some of the grape stones are rounded and granulated by gravel, and some are formed by the geological action of high temperature and high pressure in the diagenesis process. Some of the grape stones have some structural textures or cracks interspersed between the grape granules, and the shape of the plum blossoms on the epiphytic branches is called plum stone.
Physical characteristics:
Crystal system: orthorhombic system.
Crystalline state: crystalline aggregates, often in the form of plates, flakes, grapes, kidneys, radial or massive aggregates.
Cleavage: A set of complete to medium cleavage: complete cleavage; medium cleavage, aggregates are usually not seen.
Fracture: a jagged fracture.
Mohs hardness: 6 to 6.5.
Density: 2.80 g/cm3 to 2.95 g/cm3.
Other: brittle.
It has the same texture as iced chalcedony, but the hardness is not as good as the former.
Chemical properties:
Chemical composition: Ca2Al (AlSi3O10) (OH) 2, which may contain elements such as Fe, Mg, Mn, Na, K.
Chemical classification: silicate.
Edit this paragraph optical characteristics
Common colors: white, light yellow, flesh red, green, often light green.
Transparency: transparent to translucent.
Gloss: Glass luster.
Photographic characteristics: heterogeneous, biaxial crystal, positive light, often heterogeneous aggregate.
Refractive index: 1.616 ~ 1.649 (+0.016, -0.031), the point is often 1.63.
Birefringence: 0.020 ~ 0.035, the aggregate is unmeasurable.
Polychromism: None.
UV fluorescence: none.
Absorption spectrum: 438 nm weak absorption band.
Special optical effects: cat eye effect (rare).
Grape stone main producing area:
The main grape stone in our country:
Grape stone, produced in Zhangzhou, Leshan and other places in Sichuan Province. The stone color is mostly green, and there are a number of raised color blocks on the stone surface, which are like grapes, hence the name. The grape stone is mellow and smooth, crystal clear and lovely. It is better to have a contrast between the particles and the base color, and the grain is large and round, and it is also embossed to form a graphic. Some of the grape stones are rounded and granulated by gravel, and some are formed by the geological action of high temperature and high pressure in the diagenesis process. Some of the grape stones have some structural textures or cracks interspersed between the grape granules, and the shape of the plum blossoms on the epiphytic branches is called plum stone.
High-quality grape stone will produce a kind of "fluorescence" similar to the glass type of jade, very beautiful, the color of the grape stone is dark green - green gray green - green green - yellow green yellow green - yellow colorless, etc., occasionally gray. However, in general, the green-tone grape stone must have a yellow or gray color, and the yellow-tone grape stone is usually brighter but not brighter with a gray tone. In general, the color is not pure enough. The good grape stones are usually aggregates, dark green.
How to buy grape stone
Now many businessmen use green pebbles as grape stones to deceive consumers. Here's a look at the difference between the two:
First of all, in the color, I feel that the big difference is that the grape stone will have a faint glow, and the color will be more moist and slightly green.
As for weight, it is also a distinct difference. The specific gravity of the grape stone is 2.87, which is very close to the crystal. A 10MM bracelet is about 22-29-31 grams. The green banana (green garnet) with the same diameter is 3.4-3.6, and the weight should exceed 34 grams. 38 grams.
Demantoid, also known as garnet and garnet, is composed of Ca3Fe2(SiO4)3, so it is also called calcium iron garnet. The hardness is low, only 6.5. It is characterized by the unique fiber hornblende (Byssolite), which is an inclusion of asbestos fiber properties, arranged in a horsetail or radiant arrangement. This is an important basis for distinguishing green pomegranates, because it is recorded that other green gemstones do not have such inclusions.
Green pomegranate functions like other green spar, corresponding to heart and lung, circulatory system, because the mineral composition is more complex, the strength is not weak. More legends help the accumulation of wealth.
Grape pre-prehnite–Ca2Al[AlSi3O10](OH)2 orthorhombic system, the crystals are mostly grape-like, stalactite-like and granular aggregates. Transparent to translucent, the color is yellow-green, brown-yellow, gray, white to colorless. It is mostly produced in the basic igneous rocks such as gabbro and diabase, which are the products of the hydrothermal alteration of the basic plagioclase.
How to maintain the grape stone
1, natural spar, it is inevitable that there will be ice cracks and impurities, which is also a big difference between natural spar and artificial spar, so do not look at the natural crystal with a perfect eye, otherwise you will get nothing.
2, pay attention to cleaning. Generally, soak it in a thin soapy water or detergent for a while, then rinse with water for 15 minutes.
3, do not place in places with strong electromagnetic waves, such as TV, computer, audio.
4. Be careful to collide. The crystal is brittle and is easily damaged by collision with hard objects, even if the crystal collides with the crystal.
5. When the accessories are not worn, they should be packed separately and placed together with other accessories. They should also be wrapped separately.
6, the crystal cluster is the crystal matrix, its own energy source is continuous, endless. The ornaments removed each day can be placed on the crystal clusters to make them clean and energized. There are Buddhist altars that can also be placed on the altar.
7, color crystal, try to avoid long-term exposure to sunlight.
8, should not wear a crystal bath.
9, try not to wash the crystal with hot water, cold and hot and easy to damage the crystal.
10, crystal ornaments, especially necklaces or bracelets, should pay attention to the wire rope is not damaged or aging, pay more attention to the place where the wire rope and the joint meet. If the problem is found, the wire rope should be replaced in time.
11. Avoid the erosion of acid and alkali substances. The general acid and alkali are not easy to damage the crystal, but it is more likely to damage the accessories of the accessories or the metal with the crystal.
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