n. 玄武岩

[化] 玄武岩

[ noun ]
the commonest type of solidified lava; a dense dark grey fine-grained igneous rock that is composed chiefly of plagioclase feldspar and pyroxene
<noun.substance>

Basalt \Ba*salt"\, n. [L. basaltes (an African word), a dark and
hard species of marble found in Ethiopia: cf. F. basalte.]
1. (Geol.) A rock of igneous origin, consisting of augite and
triclinic feldspar, with grains of magnetic or titanic
iron, and also bottle-green particles of olivine
frequently disseminated.

Note: It is usually of a greenish black color, or of some
dull brown shade, or black. It constitutes immense beds
in some regions, and also occurs in veins or dikes
cutting through other rocks. It has often a prismatic
structure as at the Giant's Causeway, in Ireland, where
the columns are as regular as if the work of art. It is
a very tough and heavy rock, and is one of the best
materials for macadamizing roads.

2. An imitation, in pottery, of natural basalt; a kind of
black porcelain.