Diabes is green to brown, and contains plagioclase,
labradorite, olivine, hornblende, magnetite, limenite,
apatite, calcite, pyrrhotite, chalcopyrite, serpentine,
clorite, and calcite. It is a fine grained, dark
colored igneous rock composed of lath shaped plagioclase
(feldspar) crystals surrounded by smaller grains of
pyroxene and olivine. It is equivalent to the coarser
grained gabbros or diorities in chemical composition.
It commonly occurs as tabular bodies (dikes and sills)
intruded into surrounding rocks. Diabasic texture is
best seen on a weathered surface where the feldspars
stand out against the more altered mafic minerals
(minerals rich in magnesium and iron). The Palisades of
the Hudson River, near New York City, are an example.
Diabase dikes are common in areas of crustal tension,
such as the eastern coast of North America and mid ocean