Mineral properties of Diatomite

Diatomite is a kind of biological Genesis siliceous sedimentary rock, mainly composed of ancient diatom remains, its chemical composition is mainly SiO2, containing a small amount of $literal, $literal, CaO, MgO, K2O, Na2O, $literal and organic matter. 
Diatom in Diatomite has many different shapes, such as disc shape, needle shape, tube shape, feather shape and so on. The loose density is 0.3-0.5g/cm3, the MO hardness is 1~1.5 (The diatom skeleton particle is 4.5-5mm), the porosity reaches $number, can absorb its own weight 1.5-4 times times water, is the heat, the electricity, the sound bad conductor, the melting point 1650-1750°c, the chemical stability is high, In addition to hydrofluoric acid, insoluble in any strong acid, but soluble in alkali solution.