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.
The environments or conditions under which these coals were formed: anthracite coal, bituminous coal, Coals are classified into three main ranks, or types: lignite, bituminous coal, and anthracite. Lignite - is the lowest rank of coal - which means that it has the lowest heating value and lowest carbon content.