Note: Chlorhexidine may cause staining of the tooth, tooth filling, and dentures or other mouth appliances. Tetracycline use during tooth development phases (from the last half of pregnancy through eight years of age) may cause permanent discoloration (yellow, gray, brown) of teeth.
What is Coal made of? Coal is made from trees or plants that decayed on the ground for millions of years. The remains of various plants and trees then mixed with the other components of the ground and eventually going through several natural processes making them more like solid rocks.
1 However, since coal is often found interlayered with clastic rocks, we'll discuss coal with the clastic rocks.  Carbonate rocks include limestone, which is made of calcite (CaCO3), and dolostone , which is made of dolomite (CaMg(CO3)2). Dolomite often forms when limestone recrystallizes after burial.