426 Prof. A. Kenngott's Microscojncal Investigation of 



the black opaque substance in minute granules. On the right 

 (at e) is metallic iron bordered with black, and on the left, above, 

 another minute particle of iron. The dark granular substance 

 outside and above the figure is granular magnetic pyrites [troi- 

 lite) connected and framed by black opaque substance. The di- 

 stinctly linear portion of the granule touches a small portion of 

 striped grey substance below, which separates it from the iron (e) , 

 and from a diaphanous fissured granule. A number of particles 

 of the black opaque substance become visible in the interior of 

 the granule under a magnifying-power of 120 to 330. 



The third object (fig. 3) is a round granule of the grey mi- 

 neral, 0*7 millim. in diameter, nearly circular, rather distinctly 

 limited by a double row of minute opaque black granules accu- 

 mulated laterally into two black spots. The whole surface ap- 

 pears made up of white and grey under a magnifying-power of 

 75 to 120, and spotted or speckled under a higher power. Some 

 large fissures run irregularly through the whole. The double 

 border of black granules is worthy of particular notice. A mag- 

 nifying-power of 450 and more shows the whole to be inter- 

 spersed with extremely minute yellow granules, quite different 

 from the irregular yellow tints of some single places more or 

 less spread over the whole polished surface. 

 • The grey mineral constitutes essentially the round or rounded 

 granules figured in figs. 1, 2, and 3, besides many others, larger 

 and smaller, and more or less varied. All of them prove this 

 mineral to possess a certain degree of crystalline structure, as it 

 is observable in enstatite and diallage, and manifested by linear 

 stripes on the sections under certain aspects. An oblong round 

 granule of 0*8 to 1*2 millim. shows several groups of parallel 

 stripes, one near the other, as would an aggregation of a number 

 of individuals. Another granule, 0*6 millim. in diameter, pre- 

 sents very dark stripes together with lighter ones. The black 

 opaque granules along or near the margin are rarely wanting. 



Other granules consist of a compound of a transparent and 

 of a translucent mineral substance. Fig. 4 is a large round 

 granule 1*5 millim. in diameter, showing a crystalline granular 

 aggregation of the transparent silicate, with irregularly angular 

 or rounded granules cemented together by the dark-grey silicate. 

 Some few black granules appear locally, accumulated here and 

 there along the margin of the outline. A small portion of me- 

 tallic iron, bordered with a black substance, appears at e ; and at 

 another place is a dark spot of magnetic pyrites, smaller than 

 that in fig. 2, and likewise bordered with black substance. 

 Another granule, 0*8 millim. in diameter, shows within a light- 

 coloured border (about 0*08 millim. in breadth) an aggregation 

 similar to that in fig. 4, only the transparent granules are rela- 



