- Mineral (Wikipedia)
In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid substance with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.
- Aphanites (adj. aphanitic; from Ancient Greek αφανης (aphanḗs) ‘invisible’) are igneous rocks that are so fine-grained that their component mineral crystals are not visible to the naked eye (in contrast to phanerites, in which the crystals are visible to the unaided eye). This geological texture results from rapid cooling in volcanic or hypabyssal (shallow subsurface) environments. As a rule, the texture of these rocks is not the same as that of volcanic glass (e.g., obsidian), with volcanic glass being non-crystalline (amorphous), and having a glass-like appearance.
- Douglas Creek (Washington) (Wikipedia)
Douglas Creek is a creek in Douglas County, Washington. It rises in Douglas County, flows through Moses Coulee then empties to Wanapum Lake on the Columbia River. The course of the creek through Moses Coulee displays an “outdoor geologic laboratory” exhibiting basalt formations and relics of the Missoula floods of the last ice age. The watershed of Douglas Creek proper covers 132,056 acres (53,441 ha), about 11% of the county, but including McCarteny Creek the entire Moses Coulee drainage is 1,000 square miles (2,600 km2) or a little more than half of the county. The creek’s flow reaches the Columbia River “during storm water runoff events”, otherwise being absorbed into the aquifer.
- Andesite (Wikipedia)
Andesite (/ˈændəzaɪt/) is a volcanic rock of intermediate composition. In a general sense, it is the intermediate type between silica-poor basalt and silica-rich rhyolite. It is fine-grained (aphanitic) to porphyritic in texture, and is composed predominantly of sodium-rich plagioclase plus pyroxene or hornblende.
- Basalt (Wikipedia)
Basalt (UK: /ˈbæsɔːlt, -əlt/; US: /bəˈsɔːlt, ˈbeɪsɔːlt/) is an aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the surface of a rocky planet or moon. More than 90% of all volcanic rock on Earth is basalt. Rapid-cooling, fine-grained basalt is chemically equivalent to slow-cooling, coarse-grained gabbro. The eruption of basalt lava is observed by geologists at about 20 volcanoes per year. Basalt is also an important rock type on other planetary bodies in the Solar System. For example, the bulk of the plains of Venus, which cover ~80% of the surface, are basaltic; the lunar maria are plains of flood-basaltic lava flows; and basalt is a common rock on the surface of Mars.