Crystal
A chalky white borate with grey webbing — and the stone most often dyed to impersonate something else.
These are associations the community holds, not settled fact — the more a reading is shared, the bolder it sits.
Henry How, a Nova Scotian chemist and geologist, found this mineral in a gypsum quarry in 1868 after the quarrymen complained about a hard white nodule fouling their work. It is a calcium borosilicate, porous, soft at around 3.5, and marked with fine grey or black veining that looks strikingly like the matrix in turquoise.
That resemblance has determined its entire commercial life. Howlite takes dye extremely well because of its porosity, and enormous quantities of it are dyed blue and sold as turquoise, or under trade names like turquenite or white buffalo turquoise. Some of it is honestly labelled and much of it is not. If a turquoise necklace is cheap, evenly coloured and unchipped, howlite is the first thing to suspect; a chip will usually show white underneath.
Undyed, it is a perfectly good stone in its own right and practice has given it a distinct role: quiet, sleep, the lowering of a raised voice. There is something a little apt about a stone whose whole history is impersonation being assigned to calm, and practitioners who work with it tend to be fond of it precisely because it has nothing to prove.
Readings practitioners have offered, ordered by how many recognise them. Take what serves, leave the rest.
Carried forward
Common in contemporary practice
Placed under a pillow, which is one of the oldest gestures in the tradition applied to one of its newest stones — howlite was unknown to anyone before 1868. Whatever else is going on, the custom is not inherited.
Carried forward
Common in contemporary practice
Worth buying deliberately rather than by accident. Anyone who has ever owned cheap turquoise has probably owned howlite already, and knowing which stone is actually in your hand seems a reasonable minimum for working with it.
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.