C. U. Shepard—Mineralogical Notices. 55 
being half an inch, and at the smaller, but one-third. All the 
crystals have much evenness of surface and considerable 
tion. They are without striation. The color is black, with 
a slight intermixture of gray and blue. In a few instances an 
ges. The vertical cleavages, parallel with the primary prism, 
are distinct, though effected with difficulty. They take place 
parallel with the narrower planes in the quadrangular prisms. 
Only traces of a transverse cleavage exist. A marked peculi- 
arity of the larger crystals is the regular interlamination of thin 
films of white calcite, parallel with the eight sides of the prism. 
These layers, to the number of two or three, are equi-distant, 
thus imparting to the fractured ends of the crystals a checke 
aspect, strongly suggesting the structure of chiastolite.* Luster, 
resinous to vitreous. Hardness=7-... 7°. Specific grav- 
ity, 2°608. 
glass. 
Owing to the variable presence of gra hite, calcite and 
quer, the chemical examination is atten 
ae: . E. S. Dana has kindly made a section of one of the crystals, and examined 
it in polarized light. He finds “ the black color to be due to foreign matter, pres- 
nt in the form of minute grains that may be metallic, making up no small part 
of the whole,” and is of the opinion that “its analysis is not a guide to the real 
@ mineral,’ : 
