J. Ruskin — Banded and Drecciated Concretions. 



13 



Fio 



while the iron oxides root themselves on internal planes and shoot to 

 the outside. 



Hei-e (Fig. 4) is an example 

 which will at once illustrate the 

 power of the oblique force, and 

 this relation of the oxides. 



It is the section of a singly- 

 terminated, and apparently, seen 

 from the outside, an altogether 

 single, crystal, one of a well- 

 formed cluster, showing exter- 

 nally no signs of disturbance. 

 They are all beautifully spotted 

 with black iron oxide under a 

 clear external coat, about one- 

 seventh of an inch deep, which 

 entirely covers them. These con- 

 cretions of iron are represented 

 in the woodcut accurately in 

 section by the black spots ; a ^ 

 minor series, not seen exter- 

 nally, is exposed by the section 

 within the crystal, which is also shown by the section to be dual in 

 the interior, separated into two parts by a perfectly straight line in 

 the direction of its length, and nearly into two other parts by a 

 jagged and broken one across it ; all the interior beds being faulted 

 by the oblique force, which acts, — in one direction softly, guiding, 

 without breaking, one part of the white beds (opaque white in the 

 stone) into an angle beyond the other, — and in another direction 

 ■violently, causing jagged flaws across the beds. Within the white 

 beds, and under the great flaw, the quartz becomes again dark-clear. 



Now, all these arrangements of substance take place under laws 

 which surely need more investigation than they have yet received,^ 

 being quite distinct from those which limit crystalline form, and 

 bearing every semblance of a link between molecular and organic 

 structure. For instance, pure crystalline force determines both gold 

 and silver into cubes or octahedrons. So also it determines the 

 diamond. But no force of aggregation supervenes to form branches 

 or coils of diamonds ; whereas an unexplained power, dominant over 

 the crystalline one, extends the golden triangles into laminse, and 

 wreaths the cubes of silver into vermicular traceries. Agencies alike 

 inexplicable twist the crystal of quartz like a piece of red-hot iron, 

 and design the bands of agate into curves like those of a nautilus 

 shell. 



The transition from such coated crystals as that shown in Fig. 4, 



^ I look with extreme interest to the result of the inquiries which Mr. W. Chandler 

 Eoberts has undertaken on the chemistry of silica. I have to thank him already for 

 some most valuable information communicated to me ia the course of last year, of 

 which, however, I will venture no statement until he has made public his discoveriet 

 in such form as he may think proper. 



