On June 6, 1940, Mr. John Blackwood of Leadhills, while searching for gold in the alluvial wash at the head of the Shortcleuch Water, Leadhills, Lanarkshire, a spot which has for many years been the happy hunting ground of Mr. Blackwood and John D. Weir, Leadhills' two most persistent and successful gold winners, was lucky enough to discover a water-worn mass of gold in quartz weighing 501·2 grains, by far the largest and richest specimen that has been found within the memory of those living in the district. The specimen (plate I) was found while removing a mass of rock at a depth of about 3 feet, the exact spot being a few yards from the east bank of Shortcleuch Water, about midway between the ruined Lowther Cottage (wrongly shown on the six-inch Ordnance map, Lanarkshire 49 NE., as Lauder Cottage) and the junction with the Windgate Burn (Windgate Foot).

Dana classifies gümbelite in the kaolin division under pyrophyllite, and expresses the view that it may be an impure pyrophyllite. The present study, however, has shown that the unit cell of gümbelite is very similar to that of muscovite. Also the chemical analysis reveals a Closer similarity to muscovite, particularly to a variety called hydromuscovite.