Halite describes the appearance of several types of rocks and minerals. Crystals are transparent quartz that resemble ice. Igneous rocks form from volcanic magma. Metamorphic rocks were once other rocks that changed form under heat and pressure without melting. Minerals are naturally occurring inorganic substances like quartz or feldspar. Sedimentary rocks form through the deposition of sediments transported by water or ice and often contain fossils. Halite itself is typically colorless or yellow but can also appear light blue, dark blue, or pink.