348 Real and supposed effects of igneous action. 



3. The fragments 7'ese7nbllng' 7'ocks, consist of quartz, glas- 

 sy feldspar, augite, hornblende, mica, and olivine, more or 

 less blended, and mutually adherent, so as to form solid mas- 

 ses. It is impossible to say whether they are the products of 

 re-crystallization after fusion, or whether they are ejected 

 fragments thrown out from the primitive rocks, lying be- 

 neath the bed of the Pacific. They have a strong resem- 

 blance to some of the masses ejected by Vesuvius, and per- 

 haps it is most probable that they are types of the rocks, 

 in which these subterranous and submarine fires of Kirauea 

 are fed and sustained. 



4. Among the solid masses are some that very nearly re- 

 semble varieties of the Trap Rocks, basalt, and green stone, 

 ^•c. and if there had been no mistake in associating them with 

 the lava, and other decided volcanic products of these Isl- 

 ands, they would go decidedly to sustain the igneous origin 

 of the trap rocks. 



Mr. Goodrich has expressed this opinion very clear in his 

 letter. Vol. XL p. 2. 



5. Obsidian, very brilliant, black and heavy. It is rarely 

 quite free from incipient vesicular cavities, which, on the one 

 hand, graduate into those that are palpable and large, and 

 in the other, becomes evanescent in the solid substance, or 

 are discovered only by the microscope. 



6. Olivine, imbedded in large and small masses ; when 

 viewed with a magnifier, it is brilliant, and beautiful, with a 

 delicate wine yellow color, resembling, in this respect, the 

 Saxon topaz ; it appears to be very abundant in the lava of 

 Kirauea. 



7. Augite \s probably still more abundant, for the iT;elted 

 materials often exhibit decisive proof, in the black color, and 

 great weight and firmness, of having resulted extensively from 

 the fusion of this mineral and hornblende, and there appears 

 to have been a large proportion of iron present. 



8. Scorice in vast variety, and in every state of inflation, 

 from those pieces that are just beginning to pass from the 

 condition of obsidian, and compact lava, into the vesicular 



