In a recently exposed part of a quarry at Bowling, on the Clyde, my friend Mr. John Young, F.G.S., noticed a vein from an inch and half to half an inch in thickness, of a deep green mineral having the hardness and peculiar feeling of stealite, and having secured a good sample he forwarded it to me for analysis. It occurs filling a clean sided fisure on the north side of the quarry. The rock is described by Mr. Samuel Allport, F.G.S., as follows :-

“At Bowling, on the North bank of the Clyde, three miles east of Dumbarton, the rock forming the “Hill of Dun,” is a coarse crystalline dolerite, varying in colour from brownish black to black, with distinct crystals of augite, olivine, and felspar diseminated through it. This porphyritic structure is well seen in thin sections. The base is rather finely crystalline and consists of small crystals or grains of the above mentioned constituents, together with numerous grains of magnetite. The large crystals of plagioclase are clear and beautifully striated, they frequently contain glass cavities, and here and there portions, of the base have been enclosed in them . . . . This rock affords excellent examples of serpentinous pseudomorphs after olivine in various stages of formation; the crystalline forms are unusually perfect, and the gradual encroachmeut of the serpentinous matter on the clear olivine may be very well seen. In one of the sections—microscopic—an old fracture has been filled with serpentine, thus forming a vein which traverses some of the large felspar crystals and the surrounding base. A few cavities are also filled with the same substance.”