Mineralogy and Geology. 423 
_ (3.) Pyroxene Slag from Stolberg in the Hartz.—The slag is part 
glassy and part enamel-like. The crystals are yellowish-white, with 
the lustre weak resinous ; they are either 4 to 6-sided iis or oblique 
octahedral. The form may be referred to the Augite type. The oc- 
i vertical prism has the angle the corresponding to 7% (@ P3) 
of pyroxene. ier afforded M. Ley 
a #1 Mn Oa Mg K 
42°75 9°09 Ped 4°64 38819 O74 0°39 pa nl 30 
Taking 341 as replacing 28i, as Hausmann states, the oxygen ratio for 
the protoxyds and , is nearl se -" a Sie is related to those 
examined by Ram erg from 
slag has a massive base through which crystals are disseminated. The 
crystals are thin, long prisms, (about a line thick) and they appear to 
have a rectangular deny vage ; color white, with a resino- -vitreous lustre 3 
»—= 2°35; H.=6. B.B. fuses rather easily with much intumescence 
toa nee translucent blebby glass. Insoluble in muriatic acid. Analy- 
sis gave 
Bi Al Fe Mn Ca 
66°2 10-4 £3 O1 21:0 = 99°6 
giving the oxygen ratio for R, ¥, Si, 6-44 : 4:86 : 35-07, which Hausmann 
observes corresponds nearly to R Si+ Ai Si, the formula of Orthoclase, 
from which it differs in containing lime in place of potash.* 
(5.) On the blue Cx aE glassy slags.—The author adopts the view 
of Fournet (Ann ines, [4], ii, 57), that thé cause of the blue 
color is not Premal The e green color of bottle glass changes to blue 
as the glass begins to pass to the condition of enamel or an earthy state ; 
and the color is produced in this incipient stage by a new grouping of 
the minute particles of the mass. Another kind of blue slag, having 
lavender-blue to ultramarine or indigo-blue color, is supposed to derive 
its color (like ultramarine) from the presence of a trace of sulphur, as 
found on analysis. 
ter an rasan of the crystalline silicates in slags, (1, Pyrox- 
* This form: Wiiataet. oh capper 1: 9:12, whit fhe sag ges 
1: 0°75 : 5-45. The two are nearly alike for 
. Ba cor the erates tye e absence of the feldspar 
t of 
alin rien Hausmann’s of aoe of this “paves in a. this sai vol. xii, 
Phi 
