254 Forty- SIXTH Report on the State Museum. 



Tock remains sensibly unaltered and the white crinoid stems unchanged 

 to within an inch of the large hornblende crystals of the eruptive rock. 

 A narrow layer of hornstone forms the intermediate band by which 

 they are firmly united into one mass. 



Specimen No. 3, marked "Boulder of eruptive rock including small 

 masses of sandstone," is a still more remarkable rock. It also closely 

 resembles the rock from Thetford, Yt., and shows great splendent, 

 black hornblendes above an inch in length, with rounded outlines from 

 resorption in the magna. It includes many superficially rusted sand- 

 stone inclosures, but the eruptive rock is very fresh. The ferruginous 

 -character and the coarse grain of the inclosures suggest that they may 

 have come from the Oneida sandstone. The slides were all cut from 

 the vicinity of the different small inclosures which swarm in the rock, 

 :and show only few brown hornblendes. These are greatly corroded by the 

 magma. One large greenish pyroxene appears having a very narrow 

 pale brown'border. Several small olivine crystals appear in the slide. 



Fragments of a pistachio-green carbonate, a half-inch long, appear 

 among the inclosures, an J, as it is freshly and coarsely crystalline, 

 seems to be a secondary formation. It gives slight effervescence with 

 oold acid, fibundant with hot acid, a strong reaction for iron, 

 and is apparently siderite. It is peculiar in showing a strong dichroism, 

 lemon green parallel to the horizontal, and colorless parallel to the ver- 

 tical axis. In the slides which are very thick some places retain their 

 green color almost unchanged through a complete revolution, and these 

 «how the negative uniaxial ring system with several rings as in calcite, 

 and as the light vibrates thus- parallel to the horizontal axes there would 

 of course be no dichroism. In other sections w^hich show by their 

 cleavage that they are cut parallel to the vertical axis, the dichroism is 

 as stated' above. 



In another large piece from the last boulder, one side is the fresh 

 3 arge grained eruptive rock with small sandstone inclosures, and this 

 fresh eruptive rock graduates in two or three inches into an equally firm 

 and fresh looking rock which contains, in a dark green ground-mass, 

 scattered large rounded isolated hornblendes, pyroxenes and fragments 

 of the eruptive rock, and many small inclosures of sandstone and lime- 

 stone, and secondary grains of deep green calcite. The green ground- 

 mass is, under the microscope, a complete felt of actinolite needles. It 

 would be an actinolite schist except that it has not been made schistose 

 by pressure. The matted actinolite needles show faint pleochroism, 

 and extinguish at 26°-30°, and in many places project finely into the 

 .<3alcite-filled cavities. 



