Extrusive Igneous rock.
Basalt is a common extrusive igneous (volcanic) rock formed from the rapid cooling of basaltic lava exposed at or very near the surface of a planet or moon.
Mineral crystal size in a rock can provide information about the cooling rate of the magma or lava from which the rock formed. For example, faster cooling results in smaller crystal size, while slower cooling leads to larger crystals. This can help geologists determine whether the rock formed deep underground (slow cooling, larger crystals) or at the surface (quick cooling, smaller crystals).
The rock is likely a rhyolite, which is an extrusive igneous rock with a composition similar to granite but formed from rapidly cooling lava, resulting in smaller crystals. Rhyolite typically exhibits a fine-grained texture due to its quick cooling process at the Earth's surface.
Smaller crystals form in igneous rocks if they are extrusive, meaning they formed at or near the Earth's surface. Because of the quick cooling of the magma/lava, there is no time for the crystal structure to expand, leaving it smaller than if it was an intrusive rock (forming inside the Earth, below the surface).
Obsidian is formed as extruded lava with a high silicon content that cools quickly. So the environment would be a volcano.
Yes. Quick cooling doesn't allow sufficient time for the crystal structure to organize.
seasons
Basalt is a fine-grained igneous rock that forms when molten rock cools rapidly on the Earth's surface. Due to the quick cooling process, basalt has small mineral crystals. It is commonly found in volcanic regions and is rich in iron and magnesium.
Basalt is a common extrusive igneous (volcanic) rock formed from the rapid cooling of basaltic lava exposed at or very near the surface of a planet or moon.
Mineral crystal size in a rock can provide information about the cooling rate of the magma or lava from which the rock formed. For example, faster cooling results in smaller crystal size, while slower cooling leads to larger crystals. This can help geologists determine whether the rock formed deep underground (slow cooling, larger crystals) or at the surface (quick cooling, smaller crystals).
Extremely rapid cooling of lava results in the formation of volcanic glass, where no crystals have time to form due to the quick cooling process. This volcanic glass is also known as obsidian and has a smooth, shiny appearance.
This depends on the rapidity of the cooling. If the cooling is very slow, then one of the granites will result, identifiable by the type and presence of macro crystals - each a different mineral.If the cooling were fairly quick, then basalt polygonswill be formed ( as seen in the Giants Causeway), and these can approach a metre in dimension. These are of course, pseudo-crystals, not crystals in the mineral sense. They are the common substrate of all the rock as it spreads out from mid-ocean ridges. They are also not uncommon in volcanic outcrops.
A fine grained igneous rock forms from Lava that escapes from the earth crust to the surface and cools and solidifies rapidly.
quick cooling
Obsidian has a glassy texture because it forms from rapidly cooling lava without much time for crystal growth. This quick cooling process prevents the formation of crystals, resulting in a smooth and reflective surface similar to glass.
Quick cooling of ejected lava results in the formation of glassy volcanic rocks, such as obsidian or pumice. These rocks are formed when the lava solidifies so rapidly that crystals do not have time to form within the rock. The resulting texture is usually smooth and non-crystalline.
The rock is likely a rhyolite, which is an extrusive igneous rock with a composition similar to granite but formed from rapidly cooling lava, resulting in smaller crystals. Rhyolite typically exhibits a fine-grained texture due to its quick cooling process at the Earth's surface.