Mr. Alpheus F. Williams, General Manager of the De Beers Consolidated Mines, discovered in December, 1928, in the Dutoitspan mine, at Kimberley, crystals of a colourless mineral so different in appearance from other minerals observed in the Kimberley mines that it appeared to him to be new and worth detailed study. The mineral was found between the 500 and 750 ft. levels in a large dolerite inclusion in the kimberlite, and is associated with apophyllite, calcite, and natrolite. Up to the present time, less than a pound of the mineral has been found, and by far the larger part of this amount is represented by a few crystals of large size (11 × 4 × 1½ cm.). On closer examination, these crystals are seen to be not a single crystal, but a group of sub-parallel individuals, a type of development that is often observed on the larger crystals of many minerals.

Tyuyamunite from Tyuya-Muyun was established as a mineral species by K. A. Nenadkevich in 1912. It is closely allied to carnotite, differing from this in containing calcium in place of potassium, and also, according to W. F. Hillebrand, in the degree of hydration. On this account the mineral has been also known as calciocarnotite.

Calcium formate, (HCOO)2Ca, is soluble in cold water, from which it crystallizes by slow evaporation. Groth gives the following data concerning the crystals of this substance :

The molecular weight is 130.1. No definite cleavage has been observed, nor does twinning occur. There seems to have been some difference of opinion regarding the degree of symmetry. Originally the crystals were described as orthorhombic (holohedral) by J. C. Heusser in 1851, and this was followed by V. von Lung (1858) and A. Schrauf (1861). Later, however, Plathan claimed to have observed unsymmetrical etch-figures which would prove the crystal to be bisphenoidal (like the strontium, barium, and lead formates), but Wagner found only etch-figures in accordance with what would be expected from bipyramidal symmetry.

Native arsenic has hitherto ranked as a distinctly doubtful British species. The following notes contain, however, an account of its occurrence at two localities in Cornwall. John Garbyin his ‘Catalogue of Minerals found in Cornwall’ states that native arsenic had been found in Dolcoath mine, Camborne, associated with ores of cobalt. Greg and Lettsom repeat this statement with a doubtful qualification. J. H. Collins also mentions Cooks Kitchen mine, Illogan, as another doubtful locality. The occurrence as an associate of smaltite and native bismuth, minerals that have on several occasions been found in Dolcoath, is by no means unlikely, although, as far as I have been able to ascertain, no specimens of native arsenic from any of these reported localities have been preserved.