The mineral gyrolite was first described by Professor Anderson of Glasgow, as a new species from the Isle of Skye; it is stated by Greg and Lettsom to occur without doubt at two localities in Greenland, and according to Heddle at Faröe. The only other notice of it that I am acquainted with is by L. Sæmann, who mentions that he examined a specimen—no locality being given—mixed or interlaminated with pectolite, and suggests that this mineral, losing its alkali, becomes gyrolite, and, losing its lime, becomes okenite. No other analysis than the original one of Professor Anderson has, I believe, been published; the following account of its occurrence among the minerals of Nova Scotia shows it in such associations as affords a mode of explaining its origin by change in apophyllite.