Reports and Proceedings — Mineralogical Society. 237 



although not so markedly in those of a more homogeneous character. 

 Scalaria occurs in division E, the upper part of which may possibly 

 just include the base of the zone of Actinocamax quadratus, or at 

 any rate may not be many feet below that base. The distribution, 

 numerical proportion, and, to some extent also, the morphological 

 character of the macroscopic fossils of the Phosphatic Chalk are 

 exceptional. The majority of the French deposits of Senonian age 

 appear to belong to a distinctly higher horizon. The authors give 

 evidence to show that a part, at least, of the phosphatized material 

 has acquired its distinctive mineralogical character on the spot. So 

 far as can be ascertained from existing data, the Phosphatic Chalk 

 is confined to a small tract of country measuring less than 3^ miles 

 from north-east to south-west by less than 1 mile from north-west to 

 south-east. It occurs as an intercalation between the normal Chalk 

 and the Lower Eocene (Reading) Beds, and occupies a structural 

 trough which coincides with, and is probably due to, a synclinal 

 flexure. 



Mineralogical Society, March 15th, 1905. Professor H. A, 

 Miers, F.R.S., President, in the chair. — Description of the big^ 

 diamond recently found at the Premier Mine, Transvaal : by 

 Dr. F. H. Hatch and Dr. G. S. Corstorphine. The stone weighed 

 over 1^ lbs., and its greatest linear dimension was 4 inches. It was 

 part (probably less than half) of a distorted octahedral crystal. — On 

 some new mineral localities in Cornwall and Devon : by A. E. I. M. 

 Russell. An account was given of various new finds of the minerals 

 anatase, scheelite, wolframite, childrenite, apatite, and connellite. — 

 On a crystal of phenakite from Africa : by L. J. Spencer. This 

 crystal, which was transparent and rich in faces, was brought back 

 together with crystals of tourmaline, corundum, and amethj'st, by 

 the Rev. A. North Wood from the Usagara Country in German East 

 Africa. — Notes on various minerals from the Binnenthal, Switzerland: 

 by G. T. Prior and G. F. Herbert Smith. Further crystallographic 

 and chemical details were given of the three new red minerals from 

 the Binnenthal, originally described by R. H. Solly, and named by 

 him Smithite (after G. F. Herbert Smith), Hutchinsonite (after 

 A. Hutchinson), and Trechmaunite (after C. 0. Trechmann). 

 Smithite is a sulpharsenite of silver, having the composition repre- 

 sented by the formula Ag As S, ; it is monoclinic with a: b :c = 

 2-2205 : 1 : 1-9570, /3 78° 40'. A perfect cleavage parallel to 100 

 distinguishes it from the other two red minerals. Hutchinsonite is 

 rhombic with a:b :c = 1-6356 : 1 : 0-7540. A prominent form is 

 140. Trechmannite is rhombohedral with c = 0-7265. The 

 symmetry is the same as that of quartz. — On a new oxychloride of 

 copper from Sierra Gorda, Chili : by G. T. Prior and G. F. Herbert 

 Smith. This new mineral, to which the name Paratacamite was 

 given, has the same chemical composition as atacamite, but begins 

 to lose its water at a higher temperature than that mineral. It is 

 pseudorhombohedral with rr' = 83° nearly. Twins about r are 

 common. It displays optical anomalies, for minute fragments under 



