BH250-161
Title
BH250-161
Subject
Komatiitic lava; picro-basalt
Description
Major Minerals: olivine
Minor Minerals: serpentine, oxides (chromite, magnetite), pyroxene
Texture: spinifex texture (not as common as BH250-87), equigranular olivine
Alteration: Olivine to sperentite and olivine to oxide (magnetite)
Komattite: Komatiite is an ultramafic volcanic rock rich in magnesium (MgO >18 wt.%) that formed from extremely hot, low-viscosity lava during the Archean Eon, over 2.5 billion years ago. With eruption temperatures exceeding 1600°C and magnesium contents reaching up to 30%, komatiites are dominated by olivine and typically occur in Archean greenstone belts. They are rare today due to the cooler modern mantle but provide valuable insights into early Earth’s thermal history. A hallmark feature of komatiites is spinifex texture, a distinctive bladed or skeletal growth pattern of olivine crystals that forms in the rapidly cooled upper margins of lava flows, resembling the spiky Australian Spinifex grass
Minor Minerals: serpentine, oxides (chromite, magnetite), pyroxene
Texture: spinifex texture (not as common as BH250-87), equigranular olivine
Alteration: Olivine to sperentite and olivine to oxide (magnetite)
Komattite: Komatiite is an ultramafic volcanic rock rich in magnesium (MgO >18 wt.%) that formed from extremely hot, low-viscosity lava during the Archean Eon, over 2.5 billion years ago. With eruption temperatures exceeding 1600°C and magnesium contents reaching up to 30%, komatiites are dominated by olivine and typically occur in Archean greenstone belts. They are rare today due to the cooler modern mantle but provide valuable insights into early Earth’s thermal history. A hallmark feature of komatiites is spinifex texture, a distinctive bladed or skeletal growth pattern of olivine crystals that forms in the rapidly cooled upper margins of lava flows, resembling the spiky Australian Spinifex grass
Coverage
Ontario Canada, Munro Township, ~ 48° 5'57.43"N, 81° 7'2.32"W
Creator
Bereket Haileab
Source
From the rock collection of Bereket Haileab. Sample 161. Housed at Carleton College in Minnesota.
Contributor
Bereket Haileab
Type
Thin section
Relation
Collection
Citation
Bereket Haileab, “BH250-161,” BH250 Mineralogy Teaching Collection, accessed April 24, 2026, https://bereket-haileab.geology.sites.carleton.edu/items/show/305.