Vol. 52.] GRANOPHYRES OF STRATH (BETE). 325 



blende, with magnetite as a concomitant of each. Only the last of 

 these three is clearly represented in the present case ; newly-formed 

 augite has been produced only indirectly by later secretion from the 

 modified magma, and biotite has not been observed. At Carrock 

 Fell the derived augite-crystals have been completely absorbed by 

 the magma, and subsequent cr}'stallization has given rise to new 

 augite with hornblende and biotite. 



Two of the slides (2674, 6703) afford evidence of the occurrence of 

 xenocrysts of enstatite and hypersthene. There is a partial conver- 

 sion to hornblende at the margin, while the interior is serpentinized 

 or more rarely unaltered (PI. XIV. fig. 7). 



Occasionally pseudomorphs after olivine, apparently of ' pilitic ' 

 amphibole, are seen enclosed in the relics of striated augite (6704), 

 or isolated in the granophyre-matrix (6703). There is no decisive 

 criterion to determine whether these latter have come from the 

 gabbro or from destroyed basalt. 



Magnetite-grains of irregular shape are embedded in many of the 

 augite-xenocrysts and the hornblende-pseudomorphs after them, 

 and these do not differ from the grains in the original gabbro. 

 Most of the abundant magnetite in the slices is, however, of a 

 different kind, building perfect or imperfect octahedra. Though 

 partly representing in substance iron ore absorbed from gabbro- 

 debris, it is evidently a new crystallization from the modified 

 granophyre-magma. At Carrock Fell the iron ore from the gabbro 

 has been mostly, but not entirely absorbed ; its partial survival may 

 be due to its extraordinary amount and its highly titaniferous 

 nature. 



Distinct xenocrysts of gabbro-felspar are rare in the specimens 

 sliced, but they are occasionally found, especially in the neighbour- 

 hood of actual gabbro-xenoliths. One suitably oriented crystal gave 

 extinction-angles 35° and 36° in alternate lamellae, and is presumably 

 labradorite like the common felspar in the gabbros of the district. 

 It has a marginal intergrowth of a more acid felspar, and, like the 

 felspar-phenocrysts in all these granophyres, has served as nucleus 

 for a growth of micropegmatite (6704). It is clear that most of 

 the felspar of the enclosed gabbro-fragments has been completely 

 absorbed by the enveloping magma. The result is seen in a great 

 preponderance of soda-lime over potash-felspar in the rock as finally 

 consolidated, compared with the normal granophyres of the district. 

 This dominant felspar seems, however, to be chiefly the usual 

 oligoclase, with quite low extinction-angles. At Barnavave xeno- 

 crysts of felspar (bytownite) seem to be common, though they are 

 described as showing corrosion and other signs of change. 



Apart from the peculiarities described, the rocks here dealt with 

 present a general similarity to the normal granophyres. There are, 

 however, one or two special points worth noting. Several writers, 

 in describing the phenomena of xenoliths of acid rocks in basalts 

 and diabases, have remarked a tendency to the formation of hollow 

 spaces, usually filled by later products. Indications of the same 

 tendency are not wanting in the present converse case, though 



k 9, 



