160 Notice of Minerals from New Holland. 
nearly of the size of the last figure, are of a grayish white color and 
nearly opake ; the smaller are colorless and transparent. These 
crystals are highly axotomous, the folia separating with great 
readiness parallel to P, and the faces of this cleavage present a 
high pearly lustre, though not superior to that of some of the 
faces of crystallization in the same direction. I"aces M, M vit- 
reous, some smooth and shining, others roughened and dull. Fa- 
ces a, a of the pyramids, with few exceptions, perfectly smooth 
and brilliant, pearly. The proportion between the length and 
breadth of these crystals is variable ; but in the smaller and most 
perfect ones it is not less than four to one. 
The other crystals of apophyllite alluded to, are of greater di- 
mensions, measuring frequently an inch through the vertical axis 
of the prism. They are derived from a square prism, scarcely 
distinguishable, in the comparative length of the lateral and basal 
ges of the crystal, from a cube, and present only simple re- 
placements on the solid angles, by perfectly smooth and brilliant 
planes of a high pearly lustre, resembling specimens in the wri- 
ter’s collection from Iceland:* The lateral faces are frequently 
composed of curved lamine ; and the mineral sometimes presents 
compound varieties, consisting of lesser individuals, flattened or 
compressed, so as to show only portions of their planes, or sec- 
tions of smaller crystals, which have been prevented, by their 
pestuel contact, from assuming their full and perfect proportions. 
are united by similar parts, so as to have their similar faces 
in parallel position with each other. The surfaces of several of 
the larger crystals are free from these combinations, having bright 
polished planes, measurable by the common goniometer, TI 
amygdaloid to which they are attached, abounds in vesicular cav- 
ities, some of which are filled by green earth and hollow nodules 
of chalcedony. 
Heulandite. _(Hemi-prismatic Kouphone- 
spar, M. )—The individuals of this species pre- 
sent the primary form, replaced on the obtuse 
solid angles by very minute scalene triangular 
planes, resembling the subjoined Fig. 5, and 
Fig. 5. 
are f which are replaced on the solid angles b 
ee saa ain case of siabciateds 3} a modification which I do not find men- 
ing before been observed in the crystals of this species. 
” 
