What is the origin of 'sleep tight'?
Read moreOne of the mysteries of the English language finally explained.
A colourless, white, or pale yellow mineral of the monoclinic crystal system which is a barium-containing feldspar, BaAl₂Si₂O₈, dimorphous with paracelsian and occurring mostly in association with manganese deposits.
Late 19th century; earliest use found in Mineralogy Magazine. From Swedish celsian from the name of Anders Celsius + -an.