The document discusses minerals found in the Earth's crust including metals like gold and silver as well as natural compounds such as oxides, carbonates, and sulphides. It describes properties of minerals such as hardness as measured by Mohs scale, solubility in water, and how they are affected by heat. Key mineral compounds mentioned are hematite, cassiterite, calcite, malachite, iron pyrite, and galena; and how minerals like metal sulphides and carbonates decompose when heated.