While examining an abandoned lead-mine in the vicinity of Stromness, in the year 1803, I found a mineral which, from its weight and appearance, I supposed to be carbonate of barytes. A few hasty experiments soon convinced me that it was a different substance; but circumstances occurring which prevented a more accurate investigation, the mineral lay neglected among the duplicates of my collection till last autumn, when having mentioned my doubts and conjectures respecting it to my friend Dr Murray of Edinburgh, I was strongly urged by that gentleman to undertake its analysis. During his short visit to Liverpool, a few preliminary experiments were begun, from which it appeared, that the mineral contained carbonate of strontia, and I have since completed its chemical examination.