Gorgona Island (Colombia)
Gorgona is a Colombian island in the Pacific Ocean situated about 28 km (17 mi) off the Colombian Pacific coast. The island is 9 km (5.6 mi) long and 2.5 km (1.6 mi) across at its widest, with a maximum height of 338 m (1,109 ft) and a total area of 26 km2 (10 sq mi). Gorgona is separated from the continent by a 270 m (890 ft) deep underwater depression.
El Viudo - rock formation south of Gorgona
Anolis gorgonae
Komatiite is a type of ultramafic mantle-derived volcanic rock defined as having crystallised from a lava of at least 18 wt% magnesium oxide (MgO). It is classified as a 'picritic rock'. Komatiites have low silicon, potassium and aluminium, and high to extremely high magnesium content. Komatiite was named for its type locality along the Komati River in South Africa, and frequently displays spinifex texture composed of large dendritic plates of olivine and pyroxene.
Komatiite lava at the type locality in the Komati Valley, Barberton Mountainland, South Africa, showing the distinctive "spinifex texture" formed by dendritic plates of olivine (scale shown by a hammer on the right edge of photo)
Komatiite sample collected from the Abitibi greenstone belt near Englehart, Ontario, Canada. Specimen is 9 cm wide. Bladed olivine crystals are visible, though spinifex texture is weak or absent in this sample.
Graph of komatiite geochemistry MgO% vs Cr ppm, from basal flows, Wannaway, Western Australia
Photomicrograph of a thin section of komatiite showing spinifex texture of pyroxene needle-like crystals
