July 2024: Celestine

July 2024: Celestine

  • Chemical Formula: SrSO4
  • Moh's Hardness Scale: 3.0 to 3.5

Celestine, AKA celestite, is a lovely sky-blue mineral that takes its name from the heavens. These crystals are made of strontium and sulfate ions, and we get most of our industrial strontium from celestine deposits. It has some pretty explosive applications—strontium is used in fireworks to give them a deep red hue.

And possibly the coolest place we’ve ever found celestine is probably not where you’d expect. There’s a geode on South Bass Island on the Ohio side of Lake Erie that’s big enough to walk around in and is full of celestine. A winemaker discovered the geode while digging a well, and the cave became an immediate tourism hotspot. Celestine crystals in the cave can be as wide as 18 inches and weigh over 300 pounds!

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