SCIENTIFIC SUMMARY. 
331 
A Dolorite at Gleaston, in Loiu Furness. — Mr. E. W. Blnney, at a meeting 
of tlie Mancliester Philosopliical Society, gave a description of a dolorite 
found in the above locality. He thinks this place requires to he further 
investigated. The specimens were examined by Professor Koscoe, of Owen’s 
College. 
British Minerals. — In a series of admirable communications to the 
Fhilosophical Magazine, Mr. David Forbes has described, among other im- 
portant mineral productions, the stream-gold from the Diver Mawddach. 
A specimen of the dust washed from the bed of the river near Gwynfyndd, 
some eight miles from Dolgelly, contained small, flattened, elongated 
spangles of gold, the largest having the size of a pin’s head, accompanied by 
abundance of fine black sand, supposed to be magnetite, but found to be 
titanoferrite, together with some small particles of quartz, slate-rock, mica, 
iron-pyrites, and galena. The gold was found to have a specific gravity of 
15-79, and the following composition : — gold, 84-89 ; silver, 13 -99,- iron, 0-34j 
and quartz, 0 43. Several spangles had a peculiarly rich yellow colour, due 
to a thin film of sesquioxide of iron adhering to their surface. 
Titanoferrite in Stafford. — Mr. Forbes, in the memoirs above referred to, 
describes the specimen of titanoferrite found by him in Stafibrd. He states 
that the basaltic or doloritic rocks of the South Staffordshire Coalfield 
invariably contain a small amount of a heavy black metallic mineral, strongly 
attracted by the magnet, and generally regarded as magnetic oxide of iron, 
whilst analysis showed it to be titanoferrite. Removed from the pulverised 
rock by means of a magnet, it was found, on examination, to have a specific 
gravity of 4-69, and a composition closely approximating to the formula 
FegOjTiOg. The associated minerals, distinguishable only in thin sections 
when viewed under the microscope, are a' triclinic soda-lime, felspar, augite, 
and a small quantity of what is probably seladonite, whilst pyrites, apatite, 
and a zeolitic mineral are likewise occasionally present. An examination 
of specimens of these basaltic rocks from each eruptive boss in Staffordshire, 
as well as others from the intrusive masses occurring in coalpits, showed 
that titanoferrite is invariably present, and is consequently an essential 
constituent of the rock itself. It is, moreover, that variety of titanoferrite 
which usually accompanies the eruptive rocks of Palaeozoic age. The 
presence of titanium not only serves to characterise the basalts of this 
district, but likewise affords a means of detecting these rocks where altered 
by metamorphic action, and of referring tuffs, clays, etc. formed from 
them to the original source. Two instances furnishing proofs of this are 
mentioned. 
A Flack-diamond Drill. — The Artizan states that the Windsor (Vt. 
U.S.) Manufacturing Company are making a diamond drill quite different 
from the annular or tube drill (which formed a large central core and’ 
proved a failure). The new one has a solid drill-head, cutting the full size 
of the hole. This gives it greater strength and better facility for setting 
the diamonds, so as to hold their position with less liability to loosen. The 
diamonds used are dark, opaque, and imported for the purpose. They are 
worked by a small oscillating engine attached to the drill-carriage, and 
connected with a flexible supply-tube. Two men can carry one. It is 
quickly adjusted for work. The proprietors state that after boring over 
