Examination of the fisher Meteorite. — Winchell. 237 
of being isotropic and very refractive. They are drawn too 
large in comparison with the grain represented by fig. 15. 
They are really not more than one-fourth the size of that. These 
grains may all perhaps be placed in group 3, on the supposi- 
tion that they happen to lie in a position showing an optic axis. 
but on that supposition they not 
only ought to afford an optic axis 
interference figure, but they would 
agree better with group 4, on ac- 
count of the absence of cleavage. 
6. Grains that polarize in colors show no evident cleavage, 
but a tendency to fracture in a sub-eonchoidal manner with 
irregular planes of parting. Their relation to none of the 
foregoing is strong, but they might be placed in No. 3, or in 
No. 4. They are evidently from a mineral of strong charac- 
ter, but these grains do not show them favorably. Figs. 17 
and 18 seem to show an interference figure in convergent light 
resembling the axis urn (b), the optic normal.* 
Group 
Group (i. 
In all the preparations are numerous other grains which are 
largely isotropic, but charged with inclusions, some of which 
are black and some partly translucent, so that a little light 
gets through the body of the grain. But when the inclusions 
are wanting, as about the edges of the fragments, these grains 
are clear and isotropic, like No. 4 above. These grains are 
therefore, more or less obscure and partly doubly refracting. 
Careful reexamination and comparison of all the characters 
expressed in these figures seem to indicate the presence of 
four distinct different minerals, viz. : 
Group 1. Probably a loosely aggregated yet granular mass 
of olivine, rendered light by its porosity. Spots loosely sac- 
*Nos. 5, 4, 13, 16, 17 and 18 are in preparation .No. 1. Nos. 1, 12, 14 
and 19 are in preparation No. 2. Nos. <'., 7, 11, 10. 8. 15. !». 8, 2, l'.». are 
from preparation No. 3. 
