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Andesite is an aphanitic (fine-grained) to porphyritic (coarse-grained) igneous rock that is intermediate in its content of silica and low in alkali metals. It has less than 20% quartz and 10% feldspathoid by volume, with at least 65% of the feldspar in the rock consisting of plagioclase. This places andesite in the basalt /andesite field of ...
A house constructed of tuff blocks in Rieden, Rhineland-Palatinate, in the Volcanic Eifel region, Germany. Tuff is a type of rock made of volcanic ash ejected from a vent during a volcanic eruption. Following ejection and deposition, the ash is lithified into a solid rock. [1][2] Rock that contains greater than 75% ash is considered tuff, while ...
Minecraft: Story Mode is an episodic point-and-click video game developed and published by Telltale Games, based on Mojang Studios' sandbox video game Minecraft. The first five episodes were released between October 2015 through March 2016 and an additional three episodes were released as downloadable content (DLC) in mid-2016. A second season ...
Claystone – Clastic sedimentary rock composed primarily of clay-sized particles. Coal – Combustible sedimentary rock composed primarily of carbon. Conglomerate – Sedimentary rock composed of smaller rock fragments. Coquina – Sedimentary rock that is composed mostly of fragments of shells.
Gemcutting in Thailand. Lapidary (from the Latin lapidarius) is the practice of shaping stone, minerals, or gemstones into decorative items such as cabochons, engraved gems (including cameos), and faceted designs. A person who practices lapidary is known as a lapidarist. A lapidarist uses the lapidary techniques of cutting, grinding, and ...
It is an igneous rock. [6] Obsidian is produced from felsic lava, rich in the lighter elements such as silicon, oxygen, aluminium, sodium, and potassium. It is commonly found within the margins of rhyolitic lava flows known as obsidian flows. These flows have a high content of silica, granting them a high viscosity.
Lodestone. Lodestones are naturally magnetized pieces of the mineral magnetite. [1][2] They are naturally occurring magnets, which can attract iron. The property of magnetism was first discovered in antiquity through lodestones. [3] Pieces of lodestone, suspended so they could turn, were the first magnetic compasses, [3][4][5][6] and their ...
Rhyolite (/ ˈraɪ.əlaɪt / RY-ə-lyte) [1][2][3][4] is the most silica -rich of volcanic rocks. It is generally glassy or fine-grained (aphanitic) in texture, but may be porphyritic, containing larger mineral crystals (phenocrysts) in an otherwise fine-grained groundmass. The mineral assemblage is predominantly quartz, sanidine, and plagioclase.