Wordnet 3.0
NOUN (1)
1.
fine-grained homogeneous rock (such as basalt) containing minerals undetectable by the naked eye;
The Collaborative International Dictionary of English v.0.48:
Aphanite \Aph"a*nite\, n. [Gr. ? invisible; 'a priv. + ? to
appear.] (Min.)
A very compact, dark-colored ?ock, consisting of hornblende,
or pyroxene, and feldspar, but neither of them in perceptible
grains.
[1913 Webster]
WordNet (r) 3.0 (2006):
aphanite
n 1: fine-grained homogeneous rock (such as basalt) containing
minerals undetectable by the naked eye