Lava dating ca Lea cam girl from hawaii

They are tholeiitic basalts particularly low in total alkalis and in incompatible trace elements, and they have relatively flat rare earth element (REE) patterns normalized to mantle or chondrite values.

The word "basalt" is ultimately derived from Late Latin basaltes, a misspelling of Latin basanites "very hard stone", which was imported from Ancient Greek βασανίτης (basanites), from βάσανος (basanos, "touchstone") and perhaps originated in Egyptian bauhun "slate".

The modern petrological term basalt describing a particular composition of lava-derived rock originates from its use by Georgius Agricola in 1556 in his famous work of mining and mineralogy De re metallica, libri XII.

Basalt is usually grey to black in colour, but rapidly weathers to brown or rust-red due to oxidation of its mafic (iron-rich) minerals into hematite and other iron oxides and hydroxides.

Although usually characterized as "dark", basaltic rocks exhibit a wide range of shading due to regional geochemical processes.

Augite is rich in titanium compared to augite in tholeiitic basalt.

Minerals such as alkali feldspar, leucite, nepheline, sodalite, phlogopite mica, and apatite may be present in the groundmass.

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.

Flood basalt describes the formation in a series of lava basalt flows.

These phenocrysts usually are of olivine or a calcium-rich plagioclase, which have the highest melting temperatures of the typical minerals that can crystallize from the melt.

Basalt with a vesicular texture is called vesicular basalt, when the bulk of the rock is mostly solid; when the vesicles are over half the volume of a specimen, it is called scoria.

Olivine tholeiitic basalt has augite and orthopyroxene or pigeonite with abundant olivine, but olivine may have rims of pyroxene and is unlikely to be present in the groundmass.

Tags: , ,