Definition: Apollodiorite is a mineral formed by combining two types of feldspar: quartz and plagioclase. It occurs in the Earth's crust, forming layered deposits. It is named after Greek philosopher Plato, known for his discussions on wisdom. Its primary function is to provide hardness and resistance to corrosive substances like acid rain. The word is related to "apology," referring to contrition or remorse over an action that led to a negative outcome.