Minerals and Rocks
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21 terms
Terms | Definitions |
|---|---|
 mineral | a solid, naturally-occuring obj w/a defined chemical composition. inorganic w/a crystalline structure, the building blocks of rocks |
| silicate | silicon plus oxygen or silicon dioxide (SiO2), Quartz and feldspar group silicates make up most of Earth's continental crust |
| non-silicate | Many important mineral groups are not silicates.These include the carbonates, oxides, halides, sulfides, sulfates, and native metals. The non-silicate groups are a source of many valuable ore minerals and building materials. To be an ore, a mineral must occur in large enough quantities to be economically recoverable. |
| Rock | A rock is a naturally formed consolidated solid mixture containing minerals, rock fragments, or volcanic glass The terms igneous, sedimentary, and metamorphic refer to how a rock was formed. |
| Igneous | Made up of magma or lava |
| Sedimentary | Made from sediments |
| Metamorphic | Rocks changed by pressure or heat |
| intrusive | Igneous: Formed from magma which cools and solidifies below Earth's surface Cooling and solidification take a long time resulting in large visible crystals Coarse-grained like granite Granite is mostly found in the continents |
| extrusive | Formed from lava on or above Earth's surface Cooling and solidification takes place relatively quickly resulting in very small crystals Fine-grained like basalt Basalt is in the ocean floor |
| classification of intrusive igneous rock | Rocks that are quartz-rich and contain potassium feldspar and plagioclase feldspar are called granite. Rocks with no quartz and abundant plagioclase feldspar and pyroxene are called gabbro. |
| classification of extrusive igneous rock | These rocks may have the same compositions as intrusive igneous rocks, but they always will have different textures. Composition of the surrounding rock material will also affect the extrusive magma. A magma rich in silica (SiO2) forms rhyolite if it cools rapidly. Similarly, gabbro's fine-grained volcanic counterpart is basalt, which is a common rock in Earth's oceanic crust. If cooling starts off slowly below the surface with large crystals, but then finishes at a faster rate to form small or no crystals, the extrusive rock is called porphyry. |
| foliated | A texture in metamorphic rock which has lots of layers or bands |
| Nonfoliated | A texture in metamophic rock that has grains in more random orientations |
| Physical properties | a mineral has characteristics, a set of physical properties, but some of these properties can differ from sample to sample: cleavage, fracture, luster and streak, crystal shape, and hardness |
| Atom arrangement | The arrangement of atoms and the bonds between them can reflect the way a mineral breaks, how hard it is, and what types of crystal shape it has. |
| Cleavage | Minerals break along planes that cut across relatively weak chemical bonds, a smooth, flat surface is created. Most minerals (except metals) have one or more cleavage planes that also help in determining their identity. |
| Fracture | irregular break Some minerals do not split along well-defined flat surfaces. In such cases, a mineral will break unevenly. |
| Hardness | resistance to scratching use Mohs hardness scale- Friedrick Mohs 1812 whether a mineral can scratch another mineral |
| Luster and Streak | The way a mineral reflects light, whether it looks metalic or non-metalic...glassy or earthy(dull) or waxy Sreak: color of min. in powdered form |
| Crystal Shape | Controlled by arrangement of atoms, look at types of symmetry |
| porosity | When clasts are loose on Earth's surface, they don't fit together perfectly. The empty space in between the grains |
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