uncrystalline

[Pref. un-, and Eng. crys talline.] Min. & Petrol.: Not crystalline. Seeley, in Phillips ( Geol . , i. 254), considers the uncrystalline type to consist of a volcanic rock, originally amorphous, sometimes gla y like obsidian or tachylyte, and often in the microfelsitic state. There is a com plete transition between the uncrystalline and the semi-crystalline rocks.