Brush and Dana—Feairfield County Minerals. 121 
a rose- eres to yellowish-white, sometimes with a tinge of 
brown; crystals are occasionally coated dark reddish-brown 
from surface alteration ; the ese ” white. Transparent to 
Tae form.—The sala ie reddingite are rare and 
occur only in cavities in the massive min- 
eral. They have uniformly an octahedral 
habit ; sometimes only the unit pyramid is 
present and in other cases a second macro- 
diagonal pyramid, with the brachypinacoid 
as shown in the accompanying figure. Th 
creas belong to the ORTHORHOMBIC Sys- 
EM. The fundamental angles are as fol- 
tones — 
pap’, Wlalll = 16° 50’ 
par”, WiaWL..=. 110° 4? 
These angles S only tolerably exact, the probable error 
being as high as+ 5’. The axial ratio calculated from the 
above angles is :— 
c Ae 
7 a 
11524 1-0000 
The angles of the guerra prism (not eomerve), are 
Ix I=98° 6’ and 81° 54’.. The observed planes are: 
b, at, 010; 
Bt PRS 
1-2, 313 
ABs waporent angles are as follows, calculated from the 
axia 
pap, W1alll, = 65°16 
pap”, 111 alll, ra Me ES 
pag”, Tibatll, =: 3 
quq, Mandl xt 30° oy 
g.0", 219 913, = 88" 17° 
exe”, 219.318, = 0" 59" 
bap, ° O10K 711) = BT 92° 
et aa Ce Sk ee ae aa 
Of the above angles the only ones that admitted of exac 
Measurement were the three pyramidal angles, of which we 
have been taken as the basis of calculation and the third gave 
111» 111=65° 29, required 65° 16’. 
dingite is close y isomorphous with scorodite and stren- 
gite; the corresponding pyramidal angles for the three species 
are as follows: 
