SALMON — ON ROCKS. 
235 
(6). Ilauyne is a silicate of Al (26), Na (15), and Oa (0), combined 
witli S (12) : a variety of this last mineral, called N'osean, has a 
slightly different composition, with less sulphuric acid and Ca, and 
more Al and Isfa. O.Q. of all these minerals is about 1.0. 
35. Zeolites. These minerals are hydrated sihcates of £], Ca, and 
alcalies, or seemingly hyth-ated lime-felspars. They all contain Al 
exce])t 3 {Apophyllile, Damourite, and Batolite) ; and all contain Ca 
except 3 {Analcime, Natrolite, and Baryta-havmotome). The following 
list includes all the ju incipal zeolites, arranged according to their con- 
stituents : — 
iLl, Ca Scolezite, Stilbite, Heulandite, Laumonite, Leon- 
hardite. 
^1, Ca, Na . . Thomsonite (Comptonite), Epistilbite, Faujasite, 
Mesolite. 
Al, Ca, li . . . Chabasite, Phillipsite (Lime-haiTOotome) (some 
Na). 
Al . . . Na. . . Analcime, Natrolite (Mesotype). 
Al Ba. Barytarharmotome.* 
Ca, Ba, and Strontia. Brewsterite.* 
. . Ca, K . . . Apophyllite, Damouiite. 
. . Ca .... Datolite (with Boracic acid). 
36. Andalusite [1.33] ; Chiastolite. Essentially an anhydrous silicate 
of Al with very often some Fe. Chiastolite is a variety with a 
peculiar internal structure. Bischof supposes Andalusite to originate, 
in many instances, from felspars. In the conversion of felspars into 
kaolin there is a diminution of Si, and an increase of Al ; and, Lf this 
process were continued further, the composition of Andalusite would 
be ultimately attained. From pseudomorphs, we find that Andalusite 
and Chiastolite are convertible into Steatite, and the latter (Chias- 
tolite) into Talc. 
37. Kyanite, Disthene [1.5]. Composition essentially the same as that 
of Andalusite, which mineral is found, by pseudomorphs, to be con- 
vertible into Kyanite ; this alteration consists in the elimination of 
the extra Si, which gives the lower O.Q. to Andalusite, and may be 
considered as a continuation of the before-mentioned process of 
alteration of felspars into Andalusite. 
38. Wernerite, ScapoUte [.75] ; Meimite [1.0]. This mineral is essen- 
tially a silicate of Al and Ca (17), but almost always contains alcalies, 
either Na alone, or Na with a small proportion of K : the alcalies 
* These obscure minerals are noticeablu as being tlie only silicates of Baryta known in the 
mineral kingdom. 
