Search results
Results From The WOW.Com Content Network
2–3 Al 3 (Al,Si) 2 Si 13 O 36 •12H 2 O. It forms as white, green to reddish tabular monoclinic tectosilicate crystals with a Mohs hardness of 3.5 to 4 and a specific gravity of 2.1 to 2.2. It commonly occurs as a devitrification product of volcanic glass shards in tuff and as vesicle fillings in basalts, andesites and rhyolites.
Obsidian (/ ə b ˈ s ɪ d i. ən, ɒ b-/ əb-SID-ee-ən ob-) [5] is a naturally occurring volcanic glass formed when lava extruded from a volcano cools rapidly with minimal crystal growth. It is an igneous rock . [ 6 ]
Magma rich in silica and poor in dissolved water is most easily cooled rapidly enough to form volcanic glass. As a result, rhyolite magmas, which are high in silica, can produce tephra composed entirely of volcanic glass and may also form glassy lava flows. [2] Ash-flow tuffs typically consist of countless microscopic shards of volcanic glass. [3]
Although helenite and obsidian are both forms of glass, helenite differs from obsidian in that it is man-made. The stone has been marketed by the jewelry industry because of its emerald-like color, good refractive index, although its durability is low. It has a hardness of just 5 to 5 ½ and chips about as easily as obsidian or window glass.
A material 400 times harder than diamond, the 12th Doctor spends 4.5 billion years in a confession dial in the episode "Heaven Sent", continually dying and being recreated, taking the aforementioned 4.5 billion years to make it out of the confession dial by punching through an Azbantium wall.
Tachylite from Kīlauea volcano in Hawaii (view is about 9 cm across) Tachylite (/ ˈ t æ k ə l aɪ t / TAK-ə-lyte; also spelled tachylyte) is a form of basaltic volcanic glass. This glass is formed naturally by the rapid cooling of molten basalt. It is a type of mafic igneous rock that is decomposable by acids and readily fusible.
For premium support please call: 800-290-4726 more ways to reach us
The expanded material is a brilliant white, due to the reflectivity of the trapped bubbles. Unexpanded ("raw") perlite has a bulk density around 1100 kg/m 3 (1.1 g/cm 3), while typical expanded perlite has a bulk density of about 30–150 kg/m 3 (0.03–0.150 g/cm 3). [2]