CRARBOURRE, ROWTOJST, A1STD MIDDLESBROUGH. 
899 
XYII. The insoluble silicates in the rocky 'portion of the Middlesbrough aerolite. 
The constituents of the insoluble part were as follow :— 
Oxygen. 
Silicic acid. 
. 
55*389 
29-54 L 
Alumina, and a little chromium 
oxide 
4-770 
2-223 
Iron protoxide. 
23*580 
5-241 
Lime. 
4-373 
1-249 
Magnesia. 
11-043 
4-417 
Alkalies. 
determined 
10-907 
99-155 
If the chief silicate in the above portion be regarded as bronzite it most closely 
resembles that met with in the meteorites of Iowa Co., Iowa, east of Marengo, which 
fell 12th February, 1875 ;* if, on the other hand, as is more probable, it be regarded as 
a lime-magnesia-iron augite it is closely allied to the augite of the stones of Stannern 
and Juyinas. The aluminous constituent is doubtless labradorite, and is probably 
present as some of the occasional chondra which are seen in a microscopic section of 
the meteorite. 
In Plate 53 the front furrowed side is shown in figs. 6 and 7 and the back view 
in fig. 8. They require no further explanation. 
* J. L. Smith, Amer. Jour. Sc. [3], vol. x., 1875, p. 363. 
