Mineralogy classified into density (often given as specific gravity); measures of mechanical cohesion (hardness, tenacity, cleavage, fracture, parting); macroscopic visual properties (luster, color, streak, luminescence, diaphaneity); magnetic and electric properties; radioactivity and solubility in hydrogen chloride (). "Hardness" is determined by comparison with other minerals. In the Mohs scale, a standard set of minerals are numbered in order of increasing hardness from 1 (talc) to 10 (diamond). A harder mineral will scratch a softer, so an unknown mineral can be placed in this scale by which minerals it scratches and which scratch it. A few minerals such as calcite and kyanite
Mohs surgery spindle cell tumors, sebaceous carcinomas, microcystic adnexal carcinoma, merkel cell carcinoma, Paget's disease of the breast, atypical fibroxanthoma, and leiomyosarcoma. Because the Mohs procedure is micrographically controlled, it provides precise removal of the cancerous tissue, while healthy tissue is spared. Mohs surgery can also be more cost effective than other surgical methods, when considering the cost of surgical removal and separate histopathological analysis. However, Mohs surgery should be reserved for the treatment of skin cancers in anatomic areas where tissue preservation is of utmost importance (face, hands, feet, genitals). Mohs surgery should not be used on the trunk or extremities