Laccolith is a dome-shaped intrusive rock with level base fed by underground conduit. Forms when magma spreads horizontally through crust, forcing overlying strata upward. Critical radius determines when sill becomes laccolith. Laccoliths typically form at shallow crust depths from intermediate composition magma
Amphibolite contains hornblende, actinolite, plagioclase feldspar, and little quartz. Dark-colored, dense rock with weakly foliated or schistose structure. Often appears as salt-and-pepper due to black and white flakes
Mantle is a layer of silicate rock between crust and outer core. Makes up 67% of Earth's mass and 46% of its radius. Thickness is 2,900 kilometers, with 84% of Earth's volume. Behaves as viscous fluid on geologic time scales
Sedimentary rocks form from mineral or organic particles deposited at Earth's surface. Cover 73% of Earth's land surface but only 8% of crust volume. Deposited in layers forming bedding structures. Found on Mars and used for civil engineering and natural resources
Chalk is a soft, white, porous sedimentary carbonate rock. Composed mainly of calcite fragments from plankton skeletons. Contains 2-4% other minerals, mainly quartz and clay. Has porosity ranging from 35-47%
Obsidian is a volcanic glass formed from rapidly cooled lava. Contains 70%+ silica dioxide and variable amounts of other minerals. Forms at edges of rhyolitic lava flows with high silica content. Hard, brittle, and amorphous, fractures with sharp edges