hillebband.] NOTES ON JEFFERSONITE, ANORTHITE, ETC. 
69 
lowing analysis, it might be a mixture of a calcium-aluminum garnet, 
troostite, and limonite. SiO, 32.09, A1 2 3 L1.12, Fe.<> ; 5.16, MnO L5.85, 
ZnO 16.89, Oa() 15.65, ILO 2.15, MgO and alk. 1.12; total 100.00. 
The other was of a richer and deeper brown, and showed such a pro- 
nounced cleavage or parting in one direction as to produce ;i lamellar 
structure. The luster was brilliant on these cleavage surfaces. Other 
directions of cleavage were apparent. The hardness was about 5.5 and 
the density 3.39 at 21.5° C. Before the blowpipe a fragment fused 
with difficulty to a light-colored blebby glass. Analysis gave: 
TiO,, FeO, P-2O5 absent. 
Neglecting the sesquioxides, alkalies, and water, this leads to the 
ratio Si0 2 : KO = l : 1.02, and the formula is that of a metasilicate 
J^'SiC^. According to Mr. English, the material submitted by him had 
been pronounced by Professor Pentleld on the basis of qualitative tests 
to be jeffersonite, a manganese-zinc pyroxene, a statement supported 
by the analysis above given, although neither the color of the mineral 
nor its quantitative composition agree with the hitherto published data. 
In Dana's Mineralogy the color is given as "greenish black, on the ex- 
posed surface chocolate brown," the density as 3.36 011 page 358, but 3.63 
on page 360. The discoverers of the species, Keating and Vanuxem, 
give 3.50-3.55 for the density and 4.5 for the hardness. The present 
mineral presents all the evidences of being fresh and unaltered, yet it is 
brown throughout, and its analysis furnishes figures widely at variance 
with those of Herrmann and of Pisani, but giving a better metasilicate 
ratio than either of their analyses. Notwithstanding these discrepan- 
cies, there is no reason for ascribing to the mineral a new subspecies 
name. The analysis is chiefly valuable as showing a wide range of 
composition for the mineral. 
8. ANORTHITE AND EPIDOTE. 
In specimens collected by T. F. Lamb at Phippsburg, Maine, these 
two minerals occur under unusual circumstances. The mass of the 
