As the saying goes, "There is no jade without cotton." Cotton is a natural mark of jade. It is both a flaw and a feature , such as the highly sought-after snowflake cotton. So how is cotton formed? What are the differences between different cottons?

Cotton, as the name suggests, is the white cotton-like flocs in jade, which mostly appear in the form of filaments, lumps, fog, dots, etc. It can be divided into structural cotton and mineral wool according to its causes.

1. Structural cotton

Structural cotton refers to the cracks or healed cracks between jadeite minerals due to the different arrangements and relationships of jadeite minerals during the formation process of jade, which appear as clumps, blocks, strips, or mist under light.

Depending on the different characteristics, structural cotton can be divided into micro-crack cotton, mineral interstitial cotton and mineral inclusion cotton at the microscopic level.

1. Micro crack cotton

It refers to the cotton produced by the tiny cracks in jade or the healed cracks. It is mostly distributed in ribbon-like or strip-like shapes and often has a certain directionality.

Strip-like cotton is mostly found in jadeite with good texture and transparency. Due to the action of tectonic stress, broken cracks and healed cracks are produced, often appearing as one or two groups of conjugated parallel bands.

Micro-cracks in jadeite

2. Mineral gap cotton

It refers to the cotton produced by the combination boundaries of the mineral particles in jade. It is distributed around the edge contours of the mineral particles, often forming grid-like cotton or lump-like or lumpy cotton. It has unclear boundaries with the surrounding matrix and is in a transitional state. It appears in ice ground with fine texture and high transparency, as well as in bean ground with a granular feel and low transparency.

In the glutinous jadeite with lower transparency, the white cotton balls have different sizes and are mostly distributed irregularly and without pattern, and the boundary between the cotton balls and the jadeite matrix is ​​blurred; in the icy ground with higher transparency, the boundary between the cotton balls and the jadeite matrix is ​​slightly clearer, but still has a strong divergent distribution.

3. Mineral inclusion cotton

This type of cotton is mainly produced by fine-grained solid, liquid or gas-liquid inclusions contained in the formation of jadeite minerals. It is often densely distributed in single jadeite minerals, forming mist-like, flaky or lump-like cotton wool. At the microscopic level, it also appears in the form of tiny impurities wrapped in internal minerals.

▲Mineral inclusions in jadeite

In short, structural cotton can exist in jadeite with different textures, and different types of structural cotton may also exist at the same time. In jadeite with higher transparency, such as glass and ice jadeite, the jadeite mineral aggregates have relatively fine crystals and a tight structure, and there are relatively fewer micro-crack cotton and mineral interstitial cotton.

In jadeite with poor transparency such as bean-ground, dry white ground, and porcelain ground, due to the loose structure, the jadeite mineral crystals are coarse and easy to break, resulting in relatively developed micro-cracks and mineral gaps, and a large amount of cotton wool will appear.

2. Mineral Wool

Mineral wool is mainly composed of different mineral combinations produced by crystallization differentiation of jadeite in the later stage, especially albite. Due to the difference in refractive index between different minerals and the different degree of binding, white cotton wool in the form of dots and clumps will be formed under the irradiation of light.

Mineral wool mainly exists in the form of symbiotic or associated minerals of jade, distributed in irregular dots and clusters. It is mostly found in jade with a fine texture, such as ice-ground with high transparency, oily green, blue water and black jade with good texture, such as the very familiar Mu Na snowflake cotton.

From a macroscopic perspective, this type of mineral wool has a clear boundary with the jade matrix. At the same time, on the polished surface of some raw stones, some mineral wool can be seen to have depressions due to its low hardness. In addition, when observing on the reflective surface, it can be seen that the gloss of the cotton part is different from that of other matrix parts, and the cotton part is mostly darker. This is all caused by the differences in physical phase composition.

▲ Solitary distribution of albite "mineral wool"; the reflective surface has depressions at the cotton spots

Through a gem microscope, the mineral wool is basically distributed in the jade in clumps or masses, which is significantly different from the surrounding jade minerals.

▲Transmitted light, "mineral wool" particles, clear edge boundaries

It can be seen that the presence of cotton will have an important impact on the quality of jade.

First of all, cotton will affect the color of jade . The more cotton there is, the worse the light transmittance of jade will be, which will more affect the color transmission. At the same time, the more cotton there is and the more concentrated it is, which will also affect the diffusion of color.

Secondly, cotton will affect the quality of jade, that is, the transparency of jade. Jade with a lot of cotton will look chaotic and turbid, with poor transparency and appear somewhat dull.

Of course, if we can make full use of these cotton wool characteristics for clever design and creation, or even give them unique cultural meanings, then the value of jade will be raised to a higher level.