114 
Mr Brooke 07i the Comptonite of Vesuvnis^ 
duced Ills primary form, and for which I shall retain the same 
name, includes his dodccaedre and epomUe varieties, and is the 
Kadiated :Zeolite of Werner. 
The secondary planes, however, which meet under the angles 
which he has given, do not occur on any of the crystals I have 
seen. 
The cleavage he describes parallel to the plane d. Fig. 5. is 
easily effected ; but there are also natural joints very apparent, 
parallel to the edges It Jt'\ which induce me to consider the right 
rhombic prism^ Fig. 4. as the primary form. 
In Fig. 5. the measurement of P on e or jf is 120° 30' 
These measurements have been taken by the ixiflective-gonio- 
meter on several small crystals, with tolerably bright planes. 
Supposing them correct, and that the planes e and jT result from 
a decrement, by one row on the terminal edges of the prism, the 
inclination of M on M/, Fig. 4. is nearly 101° 36', and the edge 
db is to the edge ab or be nearly in the ratio of 26 to 31. 
Tlie second species included under Stilbite by the Abbe Haiiy, 
and to which I have appropriated the name of Hcidandite^ is 
the Foliated Zeolite of Werner, and crystallises in the form of 
a right prism ^ whose bases are oblique angled parallelograms^ 
Fig. 6. This species comprehends the asiamorphique arid oeto- 
duodecimale varieties, on the latter of which figures the Abbe 
Hatty has placed four planes, which do not appear on any of the 
crystals I have examined, and which may be said to be incom- 
patible with the primaiy form of the mineral 
The planes I allude to, are four of those which he has 
marked with the four which belong to the crystal, I have 
marked with the same letter in Fig. 7. this being the form un- 
der which the mineral most frequently presents itself. It is ra- 
ther remarkable, that the Abbe should have omitted to give the 
measure of his plane T on the two adjacent planes s, or the 
measure of on the two adjacent planes s ; for, although the 
* That which has been called Red Stilbite from Dumbarton, is the Henlandite. 
