igneous
Komatiite Drill Core
Ultramafic Volcanic Rock (Spinifex Texture)
Hardness: 6-7 (for constituent minerals), Color: Dark greenish-gray to black with lighter bladed crystals, Luster: Dull to sub-vitreous, Crystal Structure: Characterized by distinctive spinifex texture featuring skeletal or dendritic olivine or pyroxene blades, Specific Gravity: 2.7-3.0
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Physical properties
Hardness: 6-7 (for constituent minerals), Color: Dark greenish-gray to black with lighter bladed crystals, Luster: Dull to sub-vitreous, Crystal Structure: Characterized by distinctive spinifex texture featuring skeletal or dendritic olivine or pyroxene blades, Specific Gravity: 2.7-3.0
Formation & geological history
Formed by the cooling of extremely hot, magnesium-rich ultramafic lava flows (typically >18% MgO) during the Archean eon, often over 2.5 to 3.5 billion years ago, in submarine environments.
Uses & applications
Used primarily in geological research, academic study, and as a collector's specimen for drill core archives.
Geological facts
Komatiites are the hottest lavas known to have erupted on Earth, with extrusion temperatures estimated to exceed 1600 degrees Celsius, which is significantly hotter than modern basaltic lavas. The spinifex texture forms from rapid crystallization in superheated, volatile-poor magmas.
Field identification & locations
Found in ancient cratons such as the Yilgarn Craton in Western Australia, the Abitibi greenstone belt in Canada, and the Barberton greenstone belt in South Africa. Identified by its dark, dense ultramafic matrix and the remarkable needle-like or blade-like spinifex crystal aggregates.
