Minerals and Their Properties

Minerals

• Minerals are naturally occurring substances with a fixed chemical composition, typically found in rocks.
• Minerals can exist as elements or compounds.
• Elemental minerals are usually inactive and unresponsive.
• Examples of elemental minerals include metallic elements (gold, silver, mercury, platinum) and non-metallic elements (carbon, sulfur).
• Elements that combine with oxygen or sulfur form compounds and become more stable.

Physical Properties

• Minerals display a variety of colors and hardness levels based on their chemical composition.
• Mineral hardness can be determined by scratching or using a sclerometer.
• Harder minerals scratch softer minerals.
• The Mohs hardness scale measures mineral hardness, with diamond being the hardest (scale 10) and calcite being relatively soft (scale 3).

Chemical Properties

• Most minerals are insoluble in water, except those containing sodium and potassium.
• Minerals containing metal oxides or carbonates react with acids, dissolving and releasing carbon dioxide gas.
• Metal oxide minerals are more stable and don't decompose easily when heated, but they produce pure metals and carbon dioxide gas when heated with carbon.
• Metal carbonate minerals decompose when heated, producing metal oxides and carbon dioxide gas, except for sodium and potassium carbonates.
• The released carbon dioxide gas will cloud lime water.
• Metal sulfides decompose when heated in air, producing metal oxides and sulfur dioxide gas.
• Sulfur dioxide gas has a strong odor and turns purple in an acidic solution of potassium permanganate.

Uses of Minerals

• Calcium oxide and calcium carbonate (limestone) are used to neutralize acidic soils.
• Calcium carbonate is also used in blast furnaces to remove impurities during iron extraction.
• Silicon dioxide (silica) found in sand has a high melting point (1713°C) and is used to make glass.
• Aluminum oxide is commonly found in sunscreens and cosmetics like nail polish and lipstick.