234 Rejoorts & Proceedings — Mineralogical Society. 



MiXERALOOICAL SOCIETY. 



March 16, 1920.- Sir William P. Beale, Bart., President, in the 



chair. 



Arthur Russell : '" On the occurT'ence of Cotunnite, Anglesite, 

 Leadhillite, and Galena on fused lead from the wreck of the Fire- 

 ship Firebrand, Falmouth Harbour, Cornwall." The specimens 

 were obtained in 1846 fiom the wreck of the fireship Firebrand, 

 which was burnt in Falmoiith Harbour about the year 1780. They 

 were found under the lead pump, most of which appeared to have 

 been melted and mixed with charcoal, and consist of slag-like 

 masses of lead, which has evidently been fused, and upon the surface 

 and interstices of which are numerous well-defined and brilliant 

 crystals of cotunnite and anglesite, and more rarely small crystals 

 of leadhillite and galena. The cotunnite crystals, which are colour- 

 less and transparent with brilliant faces, are nearly always elongated 

 in the direction of the a axis, and attain a length of 3 mm. The 

 habit is somewhat variable owing to the very unequal development 

 of the faces. The forms observed were 010, 001, 021, Oil, 012, 101, 

 111, and 112. The anglesite crystals are of rectangular habit, and 

 exhibit the forms 100, 001, 110,"^ 102, 122, and 113. The leadhillite 

 crystals, thin six-sided plates in shape, are of a brown colour and 

 show the forms 101, 201, 101, 201, 112, 111, 112, and 111. The 

 galena occurs in minute cubo-octahedra. An occurrence of cotunnite 

 formed under almost exactly similar conditions has been described by 

 A. Lacroix. Similar occurrences of lead oxychlorides at Laurium, 

 and of leadhiUite in Roman slags from the Mendip Hills, were referred 

 to. — W. Campbell Smith : " Riebeckite-rhyolite from North 

 Kordofan, Sudan." A rock found by Dr. C. G. Sehgman at the 

 base of Jebel Katul, 350 miles south-west of the Bayuda volcanic 

 field was described. — Dr. G. T. Prior : '' The Meteoric Iron of 

 Mt. Ayhff, Griqualand East, South Africa." This meteoric iron, 

 found about 1907, is a coarse octahedrite similar in character to 

 Wichita County (Brazos River) and Magura (Arva). On polished 

 and etched surfaces it shows nodules of graphite and triolite, and 

 abundant cohenite crystals arranged parallel to the octahedral 

 bands. It contains about 7 per cent of nickel. 



CORRESPONDENCE. 



GAULT AND LOWER GREENSAND NEAR LEIGHTON BUZZARD. 



Sir, — I know that my colleague. Dr. Kitchin, has always found 

 it difficult to believe that the fossiliferous limestone beneath the 

 Gault at Shenley Hill can be in its original position, and it is well 

 that he and Mr. Pringle should have undertaken an independent 

 investigation of the sections. But I am certain that they have 

 misinterpreted the evidence in supposing that the limestone has been 



