➢Luster -The appearance of the mineral surface is reflected by light.

a.metallic luster - like metals b.opaque -transparent

➢Hardness- The resistance of the mineral to being scratched.

➢Color - Physical property that has limited use due to variety of colors

➢Streak - The color of the powder mixture of a mineral, or rubbing it on a ceramic plate.

➢Transparency- The degree to which a mineral will transmit light.

➢Crystal Form/Habit- the external shape of a mineral which reflects the internal arrangement of the atoms.

➢Cleavage- Cleavage is a breaking or splitting that tends to be parallel to crystal faces.

➢Specific gravity -The weight of a mineral compared to the weight of an equal volume of water(relative density).

➢Other properties - magnetism, odor, taste, tenacity, reaction to acid, etc.

Important Minerals

Quarts - (Chemical Formula SiO2) Is one of the primary minerals that originally form by crystallization from a melt in igneous rocks. Although quartz is formed at relatively high temperature it is stable (does not breakdown or alter) at conditions present near the Earth’s surface. This quartz is a primary constituent of sand, soil and sedimentary rocks called sandstones.

Clay Minerals - are sheet silicates , thus they have a crystalline structure that allows them to break easily along parallel sheets. Clay minerals form by alteration of other minerals during the process of chemical weathering.

Calcite - ( CaCO3 or calcium carbonate) Calcite is easily dissolved in water under slightly acidic conditions. Thus calcite can be precipitated directly from water. Organisms can extract the calcium and carbonate ions from water to precipitate their shells. Thus is a primary constituent of chemical and biochemical sedimentary rocks.

Rocks

Rocks are aggregates of minerals that are held together to form consolidated mass. Three Types of Rocks Based on the Mode of Formation

● Igneous Rocks - rocks that are formed from the solidification of molten rock material (magma or lava).

a. Plutonic rocks (Intrusive) - crystallization takes place deep beneath the surface of the earth; from solidified magma underneath the earth (Examples: granite, diorite, gabbro) b. Volcanic rocks (Extrusive) - crystallization takes place on the surface of the earth; fast rate of cooling/crystallization due to huge variance in the temperature between Earth’s surface and underneath (examples: rhyolite, andesite, basalt)

Sedimentary Rocks - rocks that form near the surface of the earth through chemical precipitation from water or by cementation of loose fragments called sediments.

a. clastic sedimentary rocks-result from the cementation of loose fragments of pre- existing rock. The sedimentation occurs as a result of new minerals precipitating

in the space between grains.

b. Chemical sedimentary rock - result from direct chemical precipitation from surface waters. This usually occurs as a result of evaporation which concentrates ions dissolved in water and results in the precipitation.

c. Biochemical sedimentary rock- result from the chemical precipitation by living organisms.

Metamorphic Rocks - result when any kind of pre-existing rock is buried deep in the earth and subjected to high temperatures and pressures. Most metamorphic rocks show a texture that shows an alignment of the sheet silicate minerals.

a. Slate - a fine grained metamorphic rock consisting mostly of clay minerals that breaks easily along smooth planar surfaces.

b. Schist - a coarser grained metamorphic rock consisting of quartz and micas that breaks along irregular wavy surfaces.

c. Gneiss - a rock that show alternating light and dark color banding