Ulexite (), sometimes called TV rock or TV stone due to its unusual optical properties, is a hydrous borate hydroxide of sodium and calcium with the chemical formula . The mineral occurs as silky white rounded crystalline masses or in parallel fibers. Ulexite was named for the German chemist Georg Ludwig Ulex (1811–1883), who first discovered it. In a footnote on p. 51, the editor claimed that Ulex's mineral actually was the same mineral that the American chemist Augustus Allen Hayes had found in Chile in 1844:
Ulexite
92 words updated Jun 18, 2026, 6:45 AM