\ 



BY H. I. JENSEN. (il 1 



3. The constituents comprise felspar, a honey-yellow mineral 

 which seems to be meliphanite, magnetite, olivine, fine-grained 

 augite and apatite. The felspar phenocrysts range in basicity 

 from acid labradorite to albite. Many are zoned, the outer zone 

 being of a very acid character. The lath-shaped felspars of the 

 base appear to be anorthoclase. A very curious plienomenon 

 may be observed in some parts of the base. Viewed in plane 

 polarised light without the analyser, it looks like a pilotaxitic 

 mass of hypidiomorphic crystallites of different minerals. Yet 

 as soon as the analyser is put on, certain patches appear to con- 

 tain a base which is optically continuous over the whole area, 

 and these patches have definite crystalline outlines. They 

 behave, in fact, like phenocrysts of ver}'- acid felspar (apparently 

 anorthoclase) embracing crystallites of lime-soda felspar, meli- 

 phanite, magnetite, augite and olivine. Some of the basic felspar 

 phenocrysts merge imperceptibly into the ground-mass. Many 

 are deeply corroded, but do not merge into the ground-mass. 

 The 3^ellow mineral, provisionally termed meliphanite, is quite 

 allotrimorphic. It is rather pleochroic from yellow to greenish- 

 yellow. Some thin flakes are light green in colour. It crys- 

 tallised last, for it commonly envelops the other minerals and 

 occurs interstitial ly. The double refraction is strong and the 

 refractive index moderate. Apatite occurs in allotriomorphic 

 fragments. The magnetite is idiomorphic. The pyroxene 

 consists of minute grains and laths of colourless to greenish 

 diopside. Chlorite occurs secondary after diopside. In some 

 sections a bluish isotropic mineral, probably haiiyne, occurs 

 interstitially. 



4. Order of consolidation : 



1. Felspar Phenocrysts 



2. Olivine 



3. Magnetite 



4. Felspar — - 



5. Meliphanite 



5. Name : Pilotaxitic Meliphanite-Olivine-Basalt. 



