46 Reports and Proccedin(js — Mineralogical Sociefij. 



II. MlNERALOGICAL SoCIETi'. 



Novemher 17, 1908. — Professor H. A. Miers, F.R.S., President, in 



the Chair. 



Oa Mica from North Wales and Chlorite from Conncmara; bj' 

 Messrs. A. Hutchinson and W. Campbell Smith. A mica from 

 Tan-y-b\vlch, North Wales, is found in pale-green scales in quartz 

 veins, and approximates closely in composition to the A-ariety of 

 muscovite known as sericite. A chloritic mineral from Eecess occurs 

 in transparent hexagonal plates in the quarry whence the Connemara 

 marble is obtained. It is nearly uniaxial and positive, and was found 

 on analysis to have the composition of penninite. — On the occurrence 

 of the rare mineral Carminitc in Cornwall ; by Mr. Arthur llussell. 

 This mineral, an arsenate of iron and lead, first found at Horhausen, 

 Ilhenish Prussia, and described by F. Sandberger in 1850, was 

 discovered in Cornwall by the author in 1906. It occurs as carmine- 

 red or brown needles on crystallized scorodite, mimetite, etc, from 

 Kingston Down mine. This adds one more species to the already 

 long list of rare minerals yielded by Cornwall. — Kussian Universal 

 Instruments and Methods; by Mr. T. Y. Barker. Several of the 

 universal instruments devised and kindly lent bj- Professor E. 

 Fedoroff were exhibited and the method of working explained. 

 Among the instruments described were : the hemisphere and 

 graduated rotatory quartz compensator of Professor T. Nikitin, 

 the stereographic rule, circle-ruler, graduated mica and quartz 

 compensators, universal crystal mirror-models and globes, the micro- 

 dichroscope, and the universal microscope-stage. The great utility 

 of the latter was demonstrated by the actual determination (using 

 a simple projection apparatus and screen) of the optical constants, 

 twin-law, and chemical composition of a plagioclase twin. Methods 

 of determining birefringence and the thickness of a section Avere 

 discussed, and emphasis was laid on the special usefulness of the three- 

 legged compasses in rapid calculations by graphical methods. — On 

 the composition of the Chandakapur Meteoric Stone ; by Messrs. H. E. 

 Clarke and H. L. Bowman. This meteorite, which fell in India 

 in 1838, is of chondritic type, with numerous chondrules of varying 

 structure, and consists principally of olivine and bronzite, and about 

 5 per cent, of nickel-iron. 



coi^.RESiE'onsriDEnsrcE. 



THE TYGEEBERG ANTICLINE. 

 Sir, — I recently spent a week in the countrj- between Prince 

 Albert village and the east end of Tygerberg in order to see the 

 evidence for the inverted fold said to exist there by Dr. Sandberg.' 

 Without troubling you with details, which will be published in the 

 Ann. Rep. Geol. Com. of Cape Colony for 1908, may I state briefly 

 the results of my observations, as the question of the existence of 



' See Geol. Ma.g., 1908, p. 311. 



