Judging quality
Fine geodes are fully lined, with undamaged transparent blue crystals and no crushed edges from extraction. Color naturally fades in strong light, so bright pieces should be shaded.
Sulfate
Celestite
Strontium sulfate that lines geodes with pale sky-blue tabular crystals. Madagascan geodes are the most familiar form worldwide.
Care
Very soft and light-sensitive. Never wash; dust with a dry brush and keep out of the sun.
History & lore
Celestite burns crimson in a flame test — strontium is the source of red in fireworks.
Cultural history, recorded as tradition rather than as medical or scientific claim.
Common questions about Celestite
- What is Celestite?
- Strontium sulfate that lines geodes with pale sky-blue tabular crystals. Madagascan geodes are the most familiar form worldwide.
- How hard is Celestite and what is it made of?
- Celestite is a Sulfate-family mineral with the composition SrSO4. It crystallizes in the orthorhombic system and rates 3-3.5 on the Mohs hardness scale. It occurs in pale blue, white.
- Where does Celestite come from?
- Notable localities for Celestite include Madagascar, USA (Ohio), Egypt, Poland.
- How do you tell good Celestite from filler?
- Fine geodes are fully lined, with undamaged transparent blue crystals and no crushed edges from extraction. Color naturally fades in strong light, so bright pieces should be shaded.
- How do you care for Celestite?
- Very soft and light-sensitive. Never wash; dust with a dry brush and keep out of the sun.
See it in person
Photographs only go so far
Both rooms are open six days a week, and there is always someone happy to pull pieces out of the case so you can compare them under the light.