rocks and minerals.

aid azurite barite basalt bauxite calcite calcium carbonate casket cassiterite chemistry chromite cinnabar collectibles collection conglomerate diorite education fluorite gabbro galena geodesy geography geology granite graphite gypsum hematite hobby iron kaolin kwarz limestone magnetite malachite manganese marble mica mineral minerals nature ore ores passion perlite phosphate pyrite quartzite rock sandstone science slate sphalerite steatite stibnite stone stones teaching titanium