Minerals and Rocks Overview

Rocks vs. Minerals

• Rocks are solid aggregates made up of one or more minerals and sometimes organic materials or mineraloids.
• Minerals are naturally occurring, inorganic solids with a definite chemical composition and an orderly crystalline structure.
• Minerals are pure substances; rocks are mixtures.
• All rocks contain minerals, but not all minerals are classified as rocks.

Formation of Minerals

• Inorganic Crystallization: the process where minerals form crystals directly from liquid or gaseous state—from molten rock (magma) or solutions without biological activity.
• Recrystallization: occurs when existing minerals change due to temperature, pressure, or fluids, rearranging atoms into new crystals.
• Some minerals form from evaporation, such as halite (rock salt) when salty water evaporates.

Properties of Minerals

• Color: the presence and intensity of certain elements will determine the color of a mineral.
• Streak: color of the mineral in powdered form, when rubbed on an unglazed porcelain plate.
• Porcelain plate is also known as Streak plate.
• Luster: appearance of mineral surface in reflected light
• 3 types of Luster:

1. Metallic: bright and reflective
2. sub-metallic: dull but reflective
3. non-metallic:

KINDS OF NON-METALLIC

1. Viterous (glassy & brilliant)
2. Waxy (greasy & oily)
3. Silky (fiborous)
4. Pearly (Creamy)
5. Earthy (rough & dull)
6. Resinous (plastic)

• Hardness: resistance to scratching, measured on the Mohs scale (1–10).
• The hardest mineral on the MOHS scale is Diamond.
• Cleavage and Fracture: cleavage is breaking along flat planes; fracture is irregular breaking.
• Crystal Form: geometric shape based on atomic arrangement.
• Density: mass per unit volume; It is a direct measure of how compact the mineral is.
• Gravity: density of the mineral compared to water.
• Magnetism: ability to attract or repel magnets
• Transparency: also known as Diaphaneity, ability to allow light through minerals
• Other properties
• Odor: most minerals have no odor, unless when moistened, heated, breathed, or rubbed.
• Taste: only soluble materials have taste
• Reactivity: Carbonate minerals react visibly with acid
• Tenacity: resistance to breaking or bending of a mineral

TYPES OF TENACITY

• brittleness: ability to break powder easily
• malleability: ability to be hammered out into thin sheets
• sectility: ability to be cut into thin shaving with a knife
• ductility: ability to be drawn into wires
• flexibility: can be bent but doesnt go back to its original shape
• elasticity: can be bent and return back to its original shape

Minerals Groups

• Native Elements: contain only single element (e.g., gold).
• Silicates: made of silicon and oxygen; largest mineral group.
• Sulfides: contain sulfur with metals; heavy and brittle.
• Oxides: oxygen with one or more other elements (e.g., hematite, ruby).
• Carbonates: contain carbonate ions combined with other elements (e.g., calcite).
• Phosphates: contain positively charged metal ions with phosphate ions. (E.g., turquoise)
• Halides: combination of halogen and metals (e.g., halite and flouride).
• Mineraloids: inorganic solid that does not exhibit crystalinity; lack a crystalline structure.

Minerals in the Philippines

• Major metallic minerals: copper, gold, nickel, chromite.
• Most productive copper mines found in Benguet, Cebu, and other provinces.
• High-grade copper: found in Samar, Agusan, Isabela, Zambales, Antique, and Marinduque
• Minor metals: Lead, zinc, platinum, molybdenum, and cobalt
• Mining provides materials, jobs, and revenue but must be managed to avoid environmental damage.
• 2023 data: significant extraction of gold, copper, nickel, and chromite, with high monetary values.

Nonmetallic minerals

• limestone: used in making clayware, found in Cebu, Negros, and in Angat, Bulacan
• feldspar: used to manufacture tiles and ceramic toiletware, found in ilocos norte and pampanga
• silica: found in Palawan and Negros
• marble: for building construction, found in Romblon
• clay: used in pottery
• Red clay: Ilocos sur and norte, and Cebu
• White clay: iloilo and Camarines sur

Key Terms & Definitions

• Mineral — a naturally occurring, inorganic solid with a definite chemical composition and crystalline structure.
• Rock — an aggregate of one or more minerals or mineraloids.
• Mohs Scale — a scale (1-10) used to measure mineral hardness.
• Cleavage — the tendency of a mineral to break along flat planes.
• Fracture — irregular breakage in a mineral.
• Tenacity — describes a mineral’s resistance to breaking or deforming.
• Specific Gravity — the ratio of a mineral’s density to the density of water.
• Silicates — minerals containing silicon and oxygen, often with other elements.