As a result of a recent trip to Thetford mines, in Canada, the writer was able to secure for the National Museum, and through the courtesy of Mr B. J. Bennett, manager of the King Brothers mines, an unusually fine block of serpentine, with veins of the fibrous form, chrysotile (the so-called asbestos), which seems worthy of a special description, even though little, if anything, new is deduced relative to the origin of the material.
The block, as now on exhibition in the Museum (plate 33), is some 30 by 30 by 27 inches (76.2 by 76.2 by 68.6 centimeters) in dimensions. As seen in the plate, it is traversed from left to right by one large vein of the asbestos (chrysotile), with others not quite so wide, in an approximately vertical direction.
Confining our attention first to the horizontal vein (some 40 millimeters in . . .