Explanation

feldspar is a kind of silicate mineral with shelf structure. There are mainly four types: potassium feldspar, sodium feldspar, calcium feldspar and barium feldspar. The molecular mixture of potassium feldspar and sodium feldspar is usually called alkaline feldspar, while the molecular mixture of sodium feldspar and calcium feldspar is called plagioclase. Barium feldspar is relatively rare in nature. The fifth component usually exists in natural feldspar, but its content usually does not exceed 5%. If the content exceeds 5%, a variety of feldspar will be formed. Alkaline feldspar will form complete isomorphism at high temperature, but will form limited isomorphism at low temperature, and will be decomposed into two phases of potassium feldspar and sodium feldspar. This process will form a banded crystal structure. When potassium feldspar is dominant and sodium feldspar is embedded in potassium feldspar, it is called perthite. When sodium feldspar dominates, and potassium feldspar is embedded in sodium feldspar, it is called amiperthite. feldspar crystal is usually in the form of plate or column, and twin phenomenon is common, which mainly follows the Karbas twin law, with the Z axis as the twin axis. The color can be from gray to flesh red, with glass luster. There are two sets of complete cleavage planes in feldspar, and the cleavage angle is close to 90 °. Mohs hardness between 6 and 6.5, density between 2.5 and 2.7 g/cm 3 Between. When perthite presents light blue to milky white halo on a specific cleavage surface, it is called belomorite (or moonstone). This phenomenon is caused by the interference of light on the two-phase interface of potassium feldspar and sodium feldspar. The directional arrangement of fine hematite flakes or the ultra fine copper lead to the interference of light, producing dazzling brilliance. belomorite in feldspar is usually used as materials of gems. These feldspar minerals mainly occur in intermediate to acid igneous rocks and schist. Tianhe stone is a green microcline, which contains Rb2O (1.4% to 3.3%) and Cs2O (0.2% to 0.6%), and can also be used as materials for gemstone. feldspar can be divided into a variety of minerals according to different compositions, with different crystal structure and physical properties, including monoclinic feldspar, high sodium feldspar and low sodium feldspar. They usually exist in granite pegmatite, sodium granite, schist and some hydrothermal veins. The Ah and (r molecules in feldspar usually account for less than 5%. feldspar mainly occurs in basic rocks and corresponding volcanic rock, and is also an important component of various igneous rocks. Among them, feldspar rich in potassium can be used as raw material for ceramics, while feldspar with beautiful color and luster effect can be used as materials for gems.

Classification