A form of silica occurring in hexagonal crystals which are commonly colorless and transparent, but sometimes also yellow, brown, purple, green, etc. It is the most common of all solid minerals. See Silica.
A compact granular rock composed of quartz. It is a metamorphosed sandstone, and siliceous cement is often so blended with the quartz grains as to give the rock a nearly homogeneous texture. Primary materiel in silica brick.
A crack resulting from thermal stress induced during rapid cooling or quenching, or from stresses induced by delayed transformations some time after the article has been fully quenched.
The quench severity is characterized by the H value and relates to the rate of temperature change during quenching.
Rapid cooling of hardening; normally achieved by immersion of the object to be hardened in water, oil, or solutions of salt or organic compounds in water.