478 H. S. JEVONS, H. I. JENSEN, T, G. TAYLOR AND C. A. SUSSMILCH. 



that it must have been either secondary after felspar or 

 some other mineral, or an original product of crystallisation 

 of the magma or of the magmatic waters, and not a later 

 decomposition leached out and lodged in steam cavities. 

 Analcite of this kind is shown in a photomicrograph (Plate 

 XXXIX, fig. 3). It is the proportion roughly estimated of 

 analcite in this latter more regular form which is included 

 in the above statement of the proportions of minerals in 

 the restored rock. 



The decomposition products are serpentine after olivine 

 chlorite and chloritoid in small hexagonal scales of bluish 

 colour and part at least of the analcite ; hematite and calcite 

 in small quantities, and a zeolite, probably stilbite (heu- 

 landite), possibly secondary after analcite. 



Order of Consolidation. 



Olivine 



Ilmenite — — 



Biotite — _ 



Apatite — — 



Felspar 



Augite 



Analcite or Hauyne mineral 



Specimens D, E, F, G, H. 

 Specimens D and E are very similar to O, but contain 

 considerably more ilmenite. Biotite and pseudomorphs of 

 serpentine are still plentiful. Specimens F and G were 

 obtained just below the upper aplitic vein in the S.E. end 

 of the quarry. They contain much more ilmenite than 

 either D or E, and rather less biotite. All of these roeks 

 are too decomposed for measurement by the Rosiwal 

 method. 



Examination of sections of these specimens brings out 

 the fact that biotite and pseudomorphs of olivine decrease 

 in abundance as we proceed downwards from the outer 

 compact envelope, whereas ilmenite is on the increase. 



