oligomictic
/ˌɒlɪɡə(ʊ)ˈmɪktɪk/adjective
1 Geology. Of a sedimentary rock: consisting of a small number of dominant minerals or rock types; (of a breccia) composed of fragments of a single kind of rock.
2 Limnology. Of a tropical lake: that exhibits a stable thermal stratification and only rarely undergoes an overturn.
Origin
1930s. From oligo- + ancient Greek μικτός mixed + -ic. In sense 1 after Russian oligomiktovyj.