Crystal
Pale blue strontium sulfate — soft, fragile, and the reason distress flares burn red.
These are associations the community holds, not settled fact — the more a reading is shared, the bolder it sits.
Celestite, or celestine, is strontium sulfate, and it takes its name from the Latin caelestis for the pale sky-blue of the best crystals — a colour caused by trace impurities and lattice defects rather than by any colouring element as such. It grows in sedimentary rocks, often in geodes, and the ones from South Bass Island in Lake Erie are the largest known: a single cavity there holds crystals over forty centimetres long, and the site has been open to visitors for decades.
It is the principal ore of strontium, which matters more than it sounds. Strontium salts burn crimson, which is why they go into road flares, marine distress signals and the red in fireworks. A stone this gentle-looking supplying the red in an emergency flare is one of the better facts in mineralogy.
At 3 to 3.5 on the Mohs scale it is soft, and it cleaves readily, so celestite geodes shed points if handled much and the colour fades in strong light. Practice keeps it for quiet, for sleep and for the sort of communication that does not involve speaking — a reading that comes almost wholly from the colour and the name, both of which point straight upward.
Readings practitioners have offered, ordered by how many recognise them. Take what serves, leave the rest.
Carried forward
Common in contemporary practice
Kept in a bedroom rather than a workspace, and generally left alone once placed. Practitioners describe it as a stone that does not want handling, which is convenient given that handling genuinely damages it.
Carried forward
Common in contemporary practice
Assigned to communication of a wordless kind — prayer, listening, silence. The correspondence rests on the colour and the name and nothing else, and the name was given by a mineralogist in 1799 with no thought of any of this.
Credit what you carry. Much of this comes from living traditions, and some of it from traditions that are closed — held by particular peoples and not offered for general use. Where you know whose practice a reading came from, name them; where you don't, say that too.