The meteorite is situated on the western slope of Marengi Hill, about 150 yards from the top of the hill and close to the boundary of Mr. Jennes's farm. This place is 10 miles south-east of the Mbosi mission station in Rungwe (formerly Langenburg) district. The latitude and longitude are approximately 9°7′ S., 33°4′ E. The locality lies between Lakes Tanganyika and Nyasa, south of Lake Rukwa, and about 23 miles from the border of Northern Rhodesia.

The Dhoon granite is contained in sheets 8 SW. and 8 SE. of the 6-inch Ordnance Survey Maps of the Isle of Man. It is a bosslike intrusion of irregular outcrop (fig. 1), enclosing an area about one and one-third miles long in an east-west direction, and half a mile wide in a north-south direction. It has been intruded into rocks which form part of that division of the Manx slates known as the Lonan Flags, and has metamorphosed these to a certain extent.

In 1865 A. Breithaupt described a new mineral from Herrengrund, Hungary, to which he gave the name of fauserite. It formed very pale pink crystalline aggregates and prismatic crystals, with prism angle near 88°42′ (over a), apparently orthorhombic, and cleavage b(010). Two other prisms with angles (over a) 54°39′ and 107° 50′ were observed, and a pyramid p, giving mp= 52° ; these would correspond to forms (210), (340), and (111), and the angles are near those of epsomite. An analysis by Mollnár gave the figures shown under I below—a magnesium and manganese sulphate hexahydrate, with the molecular ratio MgSO4(Mn,Mg)SO4 = 31.62 %. There is no evidence that the analysed material (stated to be crystalline) was homogeneous.

Introduction—pyro-electricity has been investigated by various methods. Sir David Brewster heated his crystals and brought them into contact with small, very light, insulating particles: If these adhered, the presence of pyro-electricity in the crystal was inferred. He also used a very delicately suspended brass needle. Being a conductor it was attracted to a charged crystal when this was brought near to it. Hankel placed the crystal under investigation in a small bath of copper or iron filings, which was then put into a hotair oven. The filings did not entirely cover the whole crystal, but one corner, edge, or face, whichever was required, was left exposed. A very small platinum sphere connected to an electrometer was then brought near to the exposed portion. The charge induced on the sphere was taken as a measure of the charge developed at the particular spot on the crystal opposite the platinum sphere.

The present paper summarizes the facts at present known regarding a characteristic effect that is often produced in the fresh plagioclase felspars of igneous rocks by thermal metamorphism—namely the development of a special type of cloudiness caused by the appearance of minute inclusions. Reference is also made to certain wel|-known rocks in which the clouding of plagioclase felspars has been described without any suggestion that the peculiarity of the felspars is connected with thermal metamorphism.