83 
TAB. CCXLIT. 
Peruaps this is one of the most remarkable crvstallizations 
ever observed in Quartz. As the ends of the primitive 
rhomhs—see tal. 41—are so scarce, this specimen is the 
more curious, having them dispersed about it. It is parti- 
cularly so, for their being as it were nearly mackled, or in 
pairs, making a bifid-ended crystal, which is partly a 
series of these depositions, undulating in a somewhat step- 
like manner, as if formed on each other, sometimes with 
scarcely any prismatic sides, except at the lower ridge of 
the opposite rhombs. Sometimes they are nearly trifid— 
see figures 1,2 and 3. Besides these there is a very odd 
formation in two places, much resembling the semicircular 
ends of bivalve shells, partly gaping, like the fruit of some 
_ Banksie, for instance of Banksia conchifera of Geertner. 
These have smaller crystals on their outside, like the others 5 
they are rather concave within, and a little convex without. 
This specimen was sent me by my kind friend John Stack- 
house, Esq., among others favours, from Cornwall. The 
whole specimen is Quartz, a little coloured by Oxide of Iron, 
although at the back in some parts it is darker, and there 
are one or two crystals of a red tint with triedral ends, 
which correspond with the characters of the Eizen-kiesel of 
the Germans—see tab.219. This odd mackled formation 
of Quartz it was the more necessary to figure, as the 
rhomb referred to was scarcely known, and much less so 
deceiving a crystal as this, if I may so call it, which has 
but little of the usual appearance of Quartz. 
G 2 
