Wiktionary
n. A mineral specimen used in various cultural and spiritual traditions for its supposed mystical energies.
Wikipedia
Charmstone, charm-stone or charm stone is a term for types of stone or mineral artifact associated with various traditional cultures, including those of Scotland and the native cultures of California and the American southwest. Typically they are elongated or cylindrical and have been shaped by grinding or other human activity, and may be perforated and/or grooved. They are thought to have been regarded as having some religious or magical function, including being talismans, amulets or charms.
Typically, but not always, references to American examples use "charmstone", and to Scottish ones "charm-stone" or "charm stone".
Usage examples of "charmstone".
There, too, with a not unbecoming gleam of barbaric colors, shone the string of porcupine beads to which the Indian charmstone hidden in her bosom was attached.
Then she put the charmstone Talcoran had given her into the little wooden box.
She clung to the charmstone he had given her, as if that would keep him close to her.
She put them into the wooden box with his charmstone, and when no one else was in the room for a few minutes, she gave it to Ava.
Walking to a nearby table, where her comb and a small hand mirror lay, she picked up the wooden box containing the charmstone and the gold hair ornaments Talcoran had once given her.
Some were known to everyone as magical, but were difficult for most folk to activate, such as charmstones and hearthstones.
The note Bea passed to me explained that some sorcerers up in the north end of the Barony of Angels tried to bring rain with Chumash Indian charmstones, perhaps in the hope that native spirits would have more effect on the local weather than imported white man's magic.