Pumice - The Stone That Floats On Water

Pumice

Pumice is additionally referred to as pumicite in its small-grained or dirt kind, could be a igneous rock that consists of extremely sac rough textured volcanic rock

It is usually light-weight coloured. 

• Pumice is formed once super-heated, extremely controlled rock is violently ejected from a volcano
• Pumice consists of extremely microvesicular glass pyroclastic with terribly thin, semitransparent bubble walls of volcanic stone. it's usually, however not completely of silicic or felsic to intermediate in composition (e.g., rhyolitic, dacitic, andesite, pantellerite, phonolite, trachyte), however volcanic rock and alternative compositions area unit known. rock is often pale in color, starting from white, cream, blue or gray, to green-brown or black. Pumice stone forms once volcanic gases exsolving from viscous rock nucleate bubbles that cannot without delay decouple from the viscous rock before chilling to glass. rock could be a common product of explosive eruptions (plinian and ignimbrite-forming) and usually forms zones in higher components of silicic lavas. rock has a median body of ninetieth, and at first floats on water.

• Scoria differs from rock in being denser. With larger sacs and thicker vesicle walls, it sinks speedily. The distinction is that the results of the lower consistency of the rock that forms scum. once larger amounts of gas area unit gift, the result's a finer-grained kind of rock referred to as pumicite. Pumice rock is taken into account a glass as a result of it's no crystal structure. rock varies in density in line with the thickness of the solid material between the bubbles; several samples float in water. when the explosion of island, rafts of rock drifted through the Pacific for up to twenty years, with tree trunks floating among them. in reality, rock rafts disperse and support many marine species. In 1979, 1984 and 2006, underwater volcanic eruptions close to Tonga created giant rock rafts, some as giant as thirty metric linear unit that floated many kilometres to Republic of Fiji.

•  There area unit 2 main styles of vesicles. Most rock contains hollow microvesicles which will impart a glossy or fibrous material. The elongation of the microvesicles happens owing to ductile elongation within the volcanic passage or, within the case of pumiceous lavas, throughout flow. the opposite kind of vesicles area unit subspherical to spherical and result from high pressure level throughout eruption