HCl Hydrochloric acid, of great use for the removal of massive calcite or other carbonates, to expose hidden crystals. Sold diluted, as muriatic acid. Examples are tourmaline and hemimorphite. Herkimer diamond Quartz crystals found in the vicinity of Herkimer, New York. Hey's Hey's Mineral Index, a book useful for its inclusion of many old discredited names.
Highgrade ore is exceptionally rich.
To highgrade a mineral collection is to sort out the best specimens. Highgrading in the mining industry means either removing only the best ore or, more commonly, theft by miners. Halite, pyromorphite, vanadinite, and galena often form hopper crystals. One mineral occurring within another. Inclusions can also be liquid or gaseous.