A basic, dark-colored, holocrystalline, igneous rock, consisting essentially of a triclinic feldspar and pyroxene with magnetic iron; -- often limited to rocks pretertiary in age. It includes part of what was early called greenstone.
A common basic igneous rock usually occurring in dykes or sills.
A basic igneous rock mineralogically the same as basalt and gabbro, but coarser-grained than basalt and finer-grained than gabbro. The plagioclase forms lath-shaped crystals lying in all directions among irregular grains of augite, giving rise to a peculiar diabasic texture. Included in the general name of "trap."
an intrusive, mafic (dark-colored) igneous rock consisting essentially of calcium-rich plagioclase and some pyroxene mineral, usually augite. Its grain size (texture) lies between coarse-grained gabbro and fine-grained basalt.
medium grained mafic volcanic rock.
An intrusive rock consisting mostly of labradorite and pyroxene and characterized by an ophitic texture. Excellent example is the Palisade Sill along the Hudson River in NJ/NY
a dark-gray to black, fine-textured igneous rock, composed of the minerals feldspar and pyroxene
an igneous rock of basaltic composition characterized by an ophitic structure.
A dark-coloured intrusive rock, found as dykes or sills, composed of mainly feldspar, pyroxene and/or olivine; it is the shallow intrusive equivalent of basalt and gabbro.
a dark, fine grained igneous rock that generally forms dikes or irregular bodies
A granular igneous rock, dark gray to black, sometimes called dolerite.
A common intrusive rock with a crystal structure intermediate between gabbro and basalt. Between Gunflint Lake and Superior ( BWCAW Region 5) Keweenawan sills and dikes of diabase intruded up through the older slate, much of which later was eroded away, or scraped away by glaciers, leaving the harder diabase ridges which define the long narrow east/west lakes and valleys so characteristic of this area.
a fine-grained, dark-colored, crystalline, granular igneous rock related to basalt and gabbro, consisting essentially of augite and calcite plagioclase feldspar; an altered form of basalt or dolerite. [AHDOS
Diabase (IPA: ) is a mafic, holocrystalline, igneous rock equivalent to volcanic basalt or plutonic gabbro.