1892,] Mineralogy and Petrography. 771 
metacinnabarite from New Almaden, Cal., have given Melville” an 
opportunity to measure and to analyze its crystals. The mineral 
occurs in steep rhombohedral forms attached to quartz crystals, which 
in turn coat cinnabar crystals, resting in'a compact mass of this sub- 
stance and quartz. The terminations of the crystals are differently 
modified, the analogue pole containing principally the basal plane and 
rhombohedra, and the antilogue pole mainly steep scalenohedra. The 
analysis, made on impure material, gave: 
S5 Hg Fe Co Zn Mn CaCo, Res. Org. mat. Total 
13.68 78.01 .61 tr. 90 .15 4.57 63 = 99.26 
The organic matter was in the form of little black spheres imbedded 
within the crystals——If the orthopinacoids of the members of the 
heulandite group be made the orthodome }P2, Rinne” shows that its 
members may be regarded as forming an isomorphous group with stil- 
bite, harmotome and phillipsite. The axial ratios of the various min- 
erals come into accord with this view if half of ¢ is taken as the unit 
in the members of the stilbite sub-group. The chemical composition 
of the different minerals is also similar enough to oppose no objection 
to the idea, the stilbites being mixtures of R” Al, Si,O,, + 6Aq and 
R, Al, Al, Si, O + 6Aq, and the heulandites R Al, Si, O,, + 6Aq 
for heulandite proper, and R Al, Si, O + 54Aq. for epistilbite and 
brewsterite. The physical properties of all the substances mentioned 
are quite alike and their optical peculiarities are not different. The 
chloritoid of a graywacke schist from the Champion Mine, Mich., is 
similar in many respects to masonite, according to Keller and Lane.” 
It is undoubtedly triclinic with B inclined 20° to the basal cleavage. 
Its pleochroism is C = yellow, B = blue, A = green. An analysis 
gave: 
SiO, TiO, AlO, FeO, FeO MnO MgO CaO K,O Na,O H,O Total 
9499 28 34.00 10.55 20.52 tr. 1.29 59 .97 35 6.75—99.59 
Its hardness is 6.5 and density = 3.552.——-Streng” again attempts to 
solve the composition of melanophiogite and succeeds in showing that the 
sulphur in its material is not in the form of sulphate but is more prob- 
Bull. U. S. Geol. Survey, No. 78, p. 80. 
Neues Jahrb. f. Min., etc., 1892, i, p. 12. 
21A mer. Jour. Sci., Dec., 1891, p. 499. 
Neues Jahrb. f. Min., etc., 1891, ii, p. Ril. 
