[Chemical composition] often contains elements such as Fe, TI, Nb, and Ta. The content of trace elements in the composition of cassiterite has a metrical significance: the cassiterite in the pegmatite is rich in Nb and Ta, and in many cases, Ta is larger than Nb; the cassiterite in the gasification-high temperature hydrothermal deposit, The Nb and Ta contents are reduced, not more than 1%, and Nb is larger than Ta; the cassiterite in the cassiterite sulfide deposit has a low content of Nb and Ta, but is rich in the rare element In. [Crystal structure] tetragonal system; [Form] It is often a double-cone-shaped polyhedron composed of square biconical and square columns, with fine longitudinal lines on the cylinder surface; elbow-shaped twin crystals formed by {101} twin planes are common (Fig. Y-12 ). The morphology of the cassiterite varies with the formation temperature, the crystallization rate, and the impurities contained (Fig. Y-13). The cassiterite produced in the pegmatite is double-cone; the cassiterite produced in the gasification high-temperature hydrothermal deposit is double-cone-shaped; the cassiterite produced in the cassiterite deposit is often long column or needle-like, and the aggregate is often present. Irregular granules (Fig. Y-14) also have dense blocks. Figure Y-12 Crystal and twin crystal of cassiterite (quoted from Pan Zhaoyu, 1993) (a) single crystal, (b) twin crystal  square column: m{110}, a{100}; square double cone: d{101}, o{111}. Figure Y-13 Relationship between the crystal form of cassiterite and formation conditions (According to K оÑтов, 1971, cited in Chen Wu, Ji Shouyuan, 1985) Figure Y-14 Crystal aggregate of cassiterite [Physical properties] Common yellow brown to dark brown, rich in Nb and Ta, asphalt black; streaks white to pale yellow; diamond gloss. The cleavage is incomplete; the shell-like fracture is broken and the grease is shiny. Hardness 6 to 7. The relative density is 6.8 to 7.0. [Occurrence] Causes and cassiterite deposits in the genesis and acid igneous rocks, particularly granite and have a close relationship, which the gasified - Causes of high-temperature hydrothermal quartz cassiterite veins and hydrothermal sulfide deposits cassiterite most valuable. When the primary tin deposit is destroyed by weathering, the cassiterite is transferred to the sand mine. China is rich in cassiterite, and its main producing areas are in Yunnan and Nanling. For example, an old tin mine in Yunnan is known as the “Siduâ€. [identification characteristics] The crystal shape and color of cassiterite are very similar to rutile, but can be distinguished according to their cleavage, relative density and chemical reaction: mineral fine particles can be placed on zinc flakes, and a drop of HCl is added. After a few minutes, if In cassiterite, a light gray metallic tin film is formed on the surface, and neither rutile nor zircon reacts. [Main use] is the most important mineral raw material for tin. Bathroom Hardware,Shower Door Rollers,Shower Door Handles,Bathroom Hardware Sets Ningbo Zongchi Machinery Technology Co., LTD , https://www.nbdiecastservice.com
a 0 = 0.474 nm, c 0 = 0.319 nm; Z = 2. Rutile crystal structure belongs.
Cassiterite
SnO 2