thumb|right|Porcellanite from the Czech Republic
thumb|right|Porcellanite from the Czech Republic
Porcellanite or porcelanite, is a hard, dense rock somewhat similar in appearance to unglazed porcelain. It is often an impure variety of chert containing clay and calcareous matter.
Discovered by embedding cosine similarity (sentence-transformers MiniLM, 384-dim).