1871J Mining, 135 



The white topaz is not well represented in the collection, and there is great 

 confusion amongst the coloured varieties of this stone. No. 1309 is much 

 more like a spinel than a topaz, while No. 1312 is a splendid yellow sapphire. 

 No. 1318 seems only quartz. 



Of the five stones labelled as tourmalines, one, No. 1322, is certainly a 

 jargoon. The green tourmaline (Nos. 1321, 1323) is a beautiful but not brilliant 

 stone. A peculiar interest attaches to this species, owing to its optical cha~ 

 rafters. It is a striking instance of dichroism, the rich grass-green specimens 

 being perfectly opaque when viewed along instead of across the principal axis 

 of the crystal. 



Among the spinels is one of an indigo-blue colour (No. 1325)', and two fine 

 pink-coloured specimens. 



There is a splendid suite of chrysoberyls, although some of them are 

 incorrectly included under quartz and chrysolite. The precious cat's-eye, or 

 cymophane, is a variety of chrysoberyl. Its opalescence is due to its intimate 

 structure, and only appears when the light is incident at a particular angle. 

 The line of light should be straight and clear as silver wire, and shows to the 

 best advantage when the stone is of a clear green tint. 



We have not space to record the peculiarities of the remaining species 

 represented in the Townshend gift. There are moonstones and sunstones, 

 with examples of labradorite, kyanite, and pyrite, all gorgeously mounted in 

 gold coronet rings, and in many instances set off by rows of diamonds. We 

 have merely noticed the existence of this very interesting and valuable 

 collection in the hope that it may receive that attention at the hands, both of 

 artists and mineralogists, which it deserves. The names assigned to about 

 twenty of the specimens should be revised, and then we should possess in London 

 three fine suites of authentic precious stones, from which their characteristics 

 might be readily learnt. The other two public collections are in the British 

 Museum and the Geological Museum of Jermyn Street. It is greatly to be 

 desired that the specific gravity, hardness, crystalline system, and refractive 

 and dispersive power should be noted on the label of each specimen. 



A. H. C. 



PROGRESS IN MECHANICS, 



(Including Mining, Metallurgy, and Engineering). 



MINING. 



Although the Statistical Returns which for many years past have issued 

 with great regularity from the Mining Record Office, under the* direction of 

 Mr. Robert Hunt, F.R.S., have this year been delayed in publication, owing to 

 the illness of their respected editor, they have appeared sufficiently early to 

 enable us to publish in this number our usual summary of their contents. The 

 following statement shows the quantity and value of the several minerals 

 raised in the United Kingdom during the year 1869* : — 



Tons. £ 



Coal 107,427,557 .. 26,856,882! 



Iron ore 11,508,525 



Tin ore 14*725 



Copper ore 129,953 



Lead ore 96,866 



Zinc ore I5>533 



Iron pyrites 75)948 



3,732,560 



1,027,805 



519.912 



1,189,030 



49,366 



41,023 



* " Mineral Statistics of the United Kingdom for 1869." By Robert Hunt, F.R.S., Keeper 

 of the Mining Records, 

 f Calculated before any charges for movement are added. 



