1. Metallic Minerals: These minerals are opaque, meaning that they do not allow light to pass through them. They often have a shiny or metallic luster and are usually hard and dense. Examples of metallic minerals include pyrite, hematite, and magnetite.
2. Nonmetallic Minerals: These minerals are usually transparent or translucent, meaning that they allow light to pass through them. They can have a variety of colors and lusters, and are generally softer and less dense than metallic minerals. Examples of nonmetallic minerals include quartz, calcite, and feldspar.
The streak test involves rubbing a mineral against a streak plate, which is usually made of unglazed porcelain. The color of the streak left on the plate can be used to identify the mineral. Metallic minerals will typically produce a dark, shiny streak, while nonmetallic minerals will produce a light-colored or no streak at all.
