Other names for howlite include turquenite (when dyed turquoise), white turquoise, white buffalo stone, and white buffalo turquoise. This is a misleading name, since the stone is unrelated to the legend of the white buffalo or any buffalo at all, and it's also a misleading marketing attempt to equate the stone with turquoise.
Howlite is found in Newfoundland, New Brunswick, and Nova Scotia, Canada; Nevada and California, US; Mexico; and in some parts of Europe, including Germany, Turkey and Serbia. (I was surprised to finally find a stone that's not listed in Brazil - but perhaps the list was incomplete!)
When howlite isn't being formed into beads and cabochons, it is carved into ornaments or the boron in it is extracted for industrial use. Like magnesite, howlite rates about a 3.5 on Moh's scale, which is fairly soft, and softer than real turquoise, which has a hardness of 5-6. Some samples of crystalline howlite, however, were found to be as hard as 6.5 by minerologists in Nova Scotia (source) - practically as hard as quartz!
Karen McCoun wrapped this howlite cabochon into a beautiful pendant.