How many letters does the top answer for “a small calcareous concretion formed in a vein; a vein stone.” have?

The most common answer is phlebolite (10 letters).

Crossword clue: a small calcareous concretion formed in a vein; a vein stone.

2 answers found in Letterora's clue database (Wikidata facts, Open Trivia DB, WordNet and Webster definitions — all licensed sources).

phlebolite 10 letters web-def

A small calcareous concretion formed in a vein; a vein stone.

phlebolith 10 letters web-def

A small calcareous concretion formed in a vein; a vein stone.

formed of small stones. 50% similar → microlithic