Rocks and Minerals: Earth Science

Minerals are naturally occurring, inorganic solids with a specific chemical composition and crystalline structure.
They are the fundamental building blocks of rocks found in the Earth’s crust.
Key properties of minerals include luster, hardness, color, streak, crystal form, cleavage, and fracture.
Unique identification properties include magnetism, odor, taste, tenacity, and reaction to acid.

Luster: Quality and intensity of reflected light.
Hardness: Resistance to abrasion.
Color and Streak: Distinct colors can identify minerals; streak is the mineral's powdered color.
Crystal Form/Habit: External shape observed during crystal growth.
Cleavage: Ability to break along parallel planes, resulting in smooth surfaces.
Fracture: Irregular breakage with non-planar surfaces.

Silicates: Contain silicon and oxygen (e.g., quartz, feldspar).
Oxides: Composed of oxygen and one or more metal ions (e.g., hematite, sapphire).
Sulfates: Contain sulfur and oxygen anions (e.g., baryte, gypsum).
Sulfides: Contain sulfur anions (e.g., pyrite, galena).
Carbonates: Include carbonate ions (e.g., calcite, dolomite).
Native Elements: Form as individual elements; metals (e.g., gold), semi-metals (e.g., arsenic), nonmetals (e.g., sulfur).
Halides: Contain halogen elements (e.g., halite).

Formed through volcanic activity and solidification of molten rock.
Intrusive Igneous Rocks: Crystallize below Earth's surface (e.g., granite, diorite).
Extrusive Igneous Rocks: Solidify on the surface post-eruption (e.g., basalt, pumice).

Created through sedimentation and deposition of materials.
Clastic Sedimentary Rocks: Formed from mechanical weathering debris (e.g., sandstone, shale).
Chemical Sedimentary Rocks: Formed when dissolved materials precipitate (e.g., limestone).
Organic Sedimentary Rocks: Result from accumulation of plant or animal debris (e.g., coal).

Formed through heat, pressure, and chemical processes while buried deep beneath the surface.
Foliated Metamorphic Rocks: Display a layered or banded appearance due to heat and pressure.

Rocks are solid aggregates of minerals while gems are precious or semi-precious minerals cut and polished for use in jewelry.
The lesson from gems is the inherent beauty and value found in natural formations, often requiring transformation to appreciate fully.