
thumb|Minette (a type of lamprophyre), from Jáchymov in the Czech Republic
thumb|Minette (a type of lamprophyre), from Jáchymov in the Czech Republic
Lamprophyres () are uncommon, small-volume ultrapotassic igneous rocks primarily occurring as dikes, lopoliths, laccoliths, stocks, and small intrusions. They are alkaline silica-undersaturated mafic or ultramafic rocks with high magnesium oxide, >3% potassium oxide, high sodium oxide, and high nickel and chromium.
Discovered by embedding cosine similarity (sentence-transformers MiniLM, 384-dim).