• Webster's Revised Unabridged Dictionary
    • n Diabase (Min) 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.
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Century Dictionary and Cyclopedia
    • n diabase The name originally given by A. Brongniart to a rock which Haüy later designated as diorite, which name Brongniart himself adopted in preference to that of diabase. Later (in 1842) Hausmann again introduced the word diabase, and by it designated a variety of pyroxenic rock, occurring in the Harz, and characterized by the presence of chlorite in considerable quantity. At the present time the name diabase is used to designate a crystalline-granular rock, consisting essentially of augite and a triclinic feldspar, with more or less magnetite or titaniferous iron, or both, and occasionally apatite or olivin, to which is added chloritic matter in varying amount. To this chloritic material the name viridite is frequently applied, this being the substance which gives the mass the greenish color which it frequently has. Diabase is one of the rocks included under the popular designation of greenstone, and also under that of trap. It is an altered form of basalt. “The main difference between diabase and basalt appears to be that the rocks included under the former name have undergone more internal alteration, in particular acquiring the diffused ‘viridite’ so characteristic of them” (Geikie, 1885). See greenstone, trap, diorite, and melaphyre.
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Chambers's Twentieth Century Dictionary
    • n Diabase dī′a-bās a compact igneous rock, an altered form of basalt—included under the popular names greenstone and trap
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Webster's Revised Unabridged Dictionary
F. diabase, fr. Gr. a crossing or passing over, fr. ; + to go; -- so called by Brongniart, because it passes over to diorite


In literature:

They are nearly all of porphyritic diabase.
"Rough Stone Monuments and Their Builders" by T. Eric Peet
Surface eruption of diabase.
"History and Comprehensive Description of Loudoun County, Virginia" by James W. Head
Such intrusive rocks are porphyries, diabases, etc.
"The Economic Aspect of Geology" by C. K. Leith
In Devonshire diabases and tuffs are found in the middle division.
"Encyclopaedia Britannica, 11th Edition, Volume 8, Slice 3" by Various
Diabases and peridotites had been formed during the Lower Cretaceous in the San Luis Obispo region.
"Encyclopaedia Britannica, 11th Edition, Volume 7, Slice 6" by Various
Quartz porphyry, diabase and diorite appear in the Ardennes.
"Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 1" by Various
Dykes of diabase and diorite are abundant.
"Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7" by Various
The upper part of the Maluti range consists of flows of melaphyres and diabases belonging to the volcanic beds.
"Encyclopaedia Britannica, 11th Edition, Volume 3, Slice 4" by Various
In some of the folds of Arenig cherts diabase lavas appear, which occupy small lenticular areas.
"Encyclopaedia Britannica, 11th Edition, Volume 8, Slice 10" by Various
Serpentines, peridotites and diabases are interstratified with the Eocene deposits.
"Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 2" by Various