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The terms lava stone and lava rock are more used by marketers than geologists, who would likely say "volcanic rock" (because lava is a molten liquid and rock is solid). "Lava stone" may describe anything from a friable silicic pumice to solid mafic flow basalt, and is sometimes used to describe rocks that were never lava , but look as if they ...
Also called Indianite. A mineral from the lime-rich end of the plagioclase group of minerals. Anorthites are usually silicates of calcium and aluminium occurring in some basic igneous rocks, typically those produced by the contact metamorphism of impure calcareous sediments. anticline An arched fold in which the layers usually dip away from the fold axis. Contrast syncline. aphanic Having the ...
Complex volcano – Landform of more than one related volcanic centre; Cryptodome – Roughly circular protrusion from slowly extruded viscous volcanic lava; Cryovolcano – Type of volcano that erupts volatiles such as water, ammonia or methane, instead of molten rock; Diatreme – Volcanic pipe associated with a gaseous explosion
Scoria or cinder is a pyroclastic, highly vesicular, dark-colored volcanic rock formed by ejection from a volcano as a molten blob and cooled in the air to form discrete grains called clasts. [ 1 ] [ 2 ] It is typically dark in color (brown, black or purplish-red), and basaltic or andesitic in composition.
Kigilyakh – Natural tall rock pillars in Yakutia; Megalith – Large stone used to build a structure or monument; Menhir – Large upright standing stone; Monadnock – Isolated, steep rock hill on relatively flat terrain (or inselberg) Monolith (Space Odyssey) – Fictional artefacts from Arthur C. Clarke's Space Odyssey novels
Pumice is an igneous rock with a foamy appearance. The name is derived from the Latin word pumex (meaning "pumice") [13] which is related to the Latin word spuma meaning "foam". [14] In former times, pumice was called "Spuma Maris", meaning "froth of the sea" in Latin because the frothy material was thought to be hardened sea foam.
Reports of earthquakes and volcano eruptions along the Ring of Fire might lead some to believe that the level of activity in recent months is above average.
Porphyry can also form even from magma that completely solidifies while still underground. The groundmass will be visibly crystalline, though not as large as the phenocrysts. The crystallization of the phenocrysts during fractional crystallization changes the composition of the remaining liquid magma, moving it closer to the eutectic point ...