1895.] Mineralogy. 359 
lenticular masses of great extent and having a thickness of 5 to 50 
meters, enclosed in the granular limestone. It is chiefly a mixture of 
corundum and magnetite with hematite and limonite as alteration pro- 
ducts. The only accessory mineral usually apparent to the naked eye 
is margarite, but Tschermak shows that there are often present in 
small quantities both the common micas, chlorotoid, Vesuvianite, dias- 
pore, kyanite, staurolite, rutile, spinel, and pyrite. Thin sections were 
prepared and detailed descriptions are furnished of the optical’ proper- 
ties of the different constituents. The corundum is part crystallized 
and part in grains. The crystals show zonal distribution of the pig- 
ment and optical anomalies, and are frequently filled with magnetite 
and rutile inclusions. The margarite yields in lath-shaped sections a 
positive bisetrix with axial plane normal to the cleavage. Basal sec- 
tions afford a negative bisectrix with small optical angle. The double 
refraction is lower than that of muscovite. The structure of the emery 
is quite schistose, due chiefly to the distribution of the magnetite 
` grains which form layers of variable thickness. Tschermak thinks 
that the original condition was a compact and homogeneous mass, and 
that the accessory minerals were separated out when the corundum and 
magnetite were crystallized. Analyses of the emery from Kremné and 
Renidi were made by Ludwig with the following results: 
Kremné. 
SiO, 5.64, B,O, 1.15, Al,O, 57.67, Fe,O, 33.36, MgO 0.83, CaO 0.43, 
K „Ô 0.31, "Lies on ignition, 0. 70, Total 100.09. 
Renidi. 
SiO, 5.45, B,O, 0.88, Al,O, 56.52, Fe,O, 34.65, MgO 0.43, CaO 0.90, 
Na i) 0.60, K 0 0. 40, Loss on ignition 0. 42, Total 100.25, 
A lengthy detailed description of specimens of emery from the dif- 
ferent localities closes the paper. 
Boleite and Cumengeite.—In a separate publication Cumenge‘ 
has given a more complete description than has heretofore been made 
of the interesting minerals Boleite and Cumengeite, which were 
recently found in the copper mining district of Boleo in Lower Cali- 
fornia. Boleite occurs in apparently cubic crystals of a deep indigo 
blue color in an argillaceous gangue locally known as Jaboneillo. They 
t Note sur deux espèces minérales nouvelles la Boléite et la Cumengéite, par 
M. E. Cumenge, Paris, 1893. 
