132 On the Chemical Composition of Wernerite, 
the analysis, by the absence of peroxide of iron which is 
always introduced during alteration, and by the high percen- 
tage of soda, which, so far as the author’s analyses extend, 
is never met with in decomposed Wernerite, He considers 
the oxygen ratio for this mineral to be 1:2:5. If further. 
analyses of minerals from this locality should confirm the 
formula assigned to this variety of Wernerite, it must be re- 
garded as a distinct species, which would be characterized 
by—l. the simple oxygen ratio; 2. the high percentage of 
silica; 3. the small percentage of alumina; 4. the compa- 
ratively small percentage of lime and high percentage oy 
alkalies, amounting on the whole to 10-5. 
2. Wernerite from Pargas (Finland.)—Occurs together 
with black and green augite, and small granules of apatite, 
imbedded in calcite. Colour greenish. Density 2-654. The 
powder is completely decomposed by hydro acid. 
Analysis gave :— 
Silica, . . 45°46 25°59 4: 
Alumina, , 90°96 14:94 2°48 
Peroxide of iron, trace 
Limo,;: . be iky ara 4°90 
Magnesia, . ot ae ; : 
Potash, . mpd ‘ol 0:22 5°70 O97 
i Bo 9°58 | 
Water, . ; 1:29 
98:53 
This Wernerite has been analysed by Nordenskiéld, who 
found the oxygen ratio for RO: R, O, : SiO, =0-95 : 29 : 4, 
and by Wolff, who found it=O'9 : 26: 4. 
Wolff’s analysis and that of the author present a tolerable 
agreement, particularly in the oxygen ratios, according to 
which the Wernerite of Pargas must be regarded as a distinct 
species, having the formula : 
3 (RO), SiO, +5 Q, 0, SiO,. 
PSEUDOMORPHOUS DERIVATIVES OF WERNERITE. 
~ Under this head are considered substances which possess 
the crystal form of Wernerite, but an essentially distinct 
chemical composition. 
