li·thol·o·gy 
(lĭ-thŏlə-jē)
(lĭ-thŏlə-jē)n.
1. The gross physical character of a rock or rock formation.
2. The microscopic study, description, and classification of rock.
lith′o·logic (lĭth′ə-lŏjĭk), lith′o·logi·cal adj.
lith′o·logi·cal·ly adv.
li·tholo·gist n.