Celestite

noun

1. A white, red-brown, orange, or light blue principal strontium ore, essentially strontium sulfate, SrSO4, found in sedimentary rock.
2. In mineralogy, native strontium sulphate.
3. A colourless, orange or blue mineral, strontium sulfate, SrSO4, that is an ore of strontium and constitutes the skeletons of Acantharea.
4. a mineral consisting of strontium sulphate