Structural features of Hetian jade

The main structure of Tianyu has the following six types:

1. Felt-like cryptocrystalline crystal structure: This is the most typical structure of Hetian jade (Plate I-1). It is characterized by: the tremolite particles are very fine, and the particle size cannot be distinguished under the optical microscope, and the size is uniform. Interwoven into a felt. The Hetian jade with this structure is fine and dense, and is a characteristic of high quality Hetian jade. The structure is visible in white jade, white jade, sapphire, and jade, and is closely related to the texture of Hetian jade;

2. Microfiber-cryptocrystalline crystal structure: refers to a structure consisting of fibrous tremolite and cryptocrystalline tremolite, wherein the fibrous tremolite is arranged in a weak orientation;

3, microfiber crystal structure: tremolite mostly fibrous aggregate, roughly parallel distribution;

4, microscopic cryptocrystalline crystal structure: refers to the structure mainly composed of flaky tremolite and cryptocrystalline tremolite (Plate I-2), in which the content of flaky tremolite is not high, with weak orientation Sex. When the hand specimen is observed by the naked eye, the flake-shaped tremolite exhibits speckle-like impurities; if it exists in a large amount, it will affect the quality of the jade, and it needs to be removed during the honing, so the jade texture with the structure is generally poor;

5. Microscopic sheet-like crystal structure: The tremolite particles are distributed in a leaf shape (Plate I-3), and the jade texture with this structure is generally coarse and even has no economic value;

6. Radial or braided crystal structure: The structure is less in Hetian jade (Plate I-4), which is another manifestation of fiber crystal structure, which is characterized by the accumulation of tremolite fiber particles in a braided shape. Accompanied by weak wavy extinction. It is inferred that under the condition of thermal deterioration of the aqueous solution, the tremolite is vigorously grown around the center and crystallized radially.

Hetian jade also has the following uncommon residual structure:

1. Residue structure: Residual minerals entrapped in plaque or metamorphic tremolite (Plate I-5), which are intermittently connected to the same residual minerals in the matrix along the inner and outer layers of the residual layer. This structure shows that in the in situ recrystallization of plaque or metamorphic minerals, the corresponding components of the original rock are completely absorbed and excluded, and it is formed in an environment with weak stress and insufficient reaction. It analyzes the metamorphism of Hetian jade for us. The environment and conditions provide valid evidence;

2, the crown structure: the flaky tremolite along the crystal edge of the dolomite residue is regularly arranged (Plate I-6), which proves that the dolomite in the participation of the hot aqueous solution, in the crystal grain After softening, it forms a soft king, namely dolomite + SiO2 + H20 (steam) + tremolite.