336 Reports & Proceedings—Mineralogical Society. 
obtained by the complete inversion of the structure; vice versa, in 
an inversion-twin the normal to every plane of symmetry is an axis 
of rotation-twinning, and every line of symmetry is an axis of 
reflection-twinning. If a twin-axis be at right angles to an axis 
of nm degrees of symmetry, there will be in all » twin-axes of the 
same kind at right angles to the same axis of symmetry. Other 
more complex relations were described.—Dr. G. T. Prior: The 
Meteorites of Khairpur and Soko-Banja. The Khairpur meteorite 
is precisely similar to the Daniels Kuil, and like it belongs to the 
rare Hvittis type of chondritic stones, which contain oldhamite, and 
are almost free from oxide of iron. The Soko-Banja meteorite 
contains a small amount (4 per cent) of nickel-iron, very rich in 
nickel, together with ferro-magnesian minerals, rich in ferrous oxide. 
—Dr. G.'l’. Prior: On the Classification of Meteorites. In chondritic 
stones the richer the nickel-iron in nickel the richer the ferro- 
magnesian minerals in ferrous oxide, and in general the smaller the 
amount of nickel-iron the richer it is in nickel. On these principles 
chondritic stones are divided into four groups, corresponding to the 
types: (1) Daniels Kuil, (2) Cronstad, (3) Baroti, (4) Soko-Banja. 
Under the same groups the meteoric irons may be arranged according 
to their richness in nickel, and the non-chondritic stones according to 
the richness in iron of the ferro-magnesian silicates, except that 
a fifth group is added for Eucrite, Howardite, Shergottite, Angrite, 
and Nakhlite, since they are richer in lime, ferrous oxide, and 
mostly also in alumina than any chondritic stone at present known.— 
Lieutenant A. Russell, R.E.: Note on a new occurrence of Gold from 
Cornwall. Alluvial gold was found in the bed of a small stream 
adjoining a jamesonite mine near Port Isaac.—A. Holmes: On aseries 
of Volcanic Rocks from the neighbourhood of the Lucalla River, Angola. 
The rocks described were collected by J. J. Monteiro in 1860, and 
include porphyritic basalts, biotite trachyte, trachyte with xgirine 
and cossyrite, nephelinite, and pyroxene andesite. They occur partly 
over Archean and partly over Karoo rocks, and are probably related 
to the Vertiary alkali rocks between Senza do Itombe and Bango. 
An olivine camptonite of post-Miocene age from Dombe Grande, near 
Benguella, was also described.—Professor T. L. Walker: Spencerite, 
a new Zine Phosphate from British Columbia. The new mineral 
occurs as the core of stalactites of hemimorphite in the H.B. zine- 
mine near Salmo in the West Kootenay district. It is snow-white in 
colour with brilliant pearly lustre on the perfect cleavage. The 
three rectangular cleavages and the optical characters suggest at first 
sight rhombic symmetry, but complex lamellar twinning is present, 
and etched figures are symmetrical about one plane only. Analyses 
of the very pure material conform closely with the formula Zn3. 
(PO4)2 . Zn (OH), . 3H, 0, the mineral being a hydrated basic zine 
phosphate, and thus differing from the other zine phosphates— 
hopeite, parahopeite, and tarbuttite. It is named after Mr. L. J. 
Spencer, of the British Museum.—E. L. Bruce: Magnesian Tourma- 
line from Renfrew, Ontario. Brown crystals occur at the contact of 
crystalline limestone and gneiss in a limestone quarry at the town of 
Renfrew. Analysis shows the presence of 14°58 per cent of magnesia. 
