24, 
from the neighbourhood of Aberdeen, and may assist in 
explaining those of the same nature when they occur. It 
is part of a large crystal, which includes some Quartz and 
a few sparks of Mica, appearing at first a rude mis-shapen 
portion, to which I have added the outline for explanation. 
The crystal is formed of two similar halves of different 
crystals, locked as it were into each other ;—see the zigzag 
line No. 1. 
The lower left hand figure represents a single crystal, in 
which the same faces are seen as are mentioned in tab. 212; 
the largest terminal face being the primitive one ; but the 
small faces are greatly increased in size. If this crystal were 
divided in the middle in the direction of the dotted line, 
and one half turned round, it would not be in the least 
changed in form, answering nearly to Haiiy’s remark, 3. 602. 
The right hand figure is formed of two halves taken from 
the similar sides of two different crystals. (or, which is ex- 
actly the same thing, of two pieces cast in the same mould), 
each exactly corresponding with one half of the left hand 
Jigure. In this the primitive face is divided into two parts, 
and each part is brought to correspond with part of a 
secondary face, fig. 2, but may be easily distinguished by 
the fracture. 
