| Webster's Online Dictionary |
| Expressions | Domain | Definition | |
| Hardness points | Mining | Small pieces of minerals of differing hardness, with one end pointed and affixed to small handles of wood, metal, or plastic, to be held in hand and used for testing hardness of another mineral, by ascertaining which points will scratch it. Minerals of hardness 6 to 10 are usually used as points for testing gem stones. Syn: hardness gage; hardness pencils. (references) | |
Source: compiled by the editor from various references; see credits. | Top | ||
