4i8 
THE CARBONIFEROUS VOLCANOES 
KOOK VI 
not quite holo-crystalline, the crystals of felspar, augite and magnetite are 
large and the structure coarse-grained, while the groundinass is confined to 
comparatively small interstitial patches. In tliese rocks there is usually no 
one dominant porphyritic ingredient.” 
I. The Olivixe-beaeikg Series 
1. Olivine -Bolerites 
la. Porphyritic elements inconspicuous, olivine being the] 
principal, and felspar of secondary importance ; ground- -Jedburgh Type, 
mass sub-ophitie. I 
1/). Strongly porphyritic ; felspar-phenocrysts large : olivinef _ 
smaller ; groundinass sub-ophitic. j-Kilsytli Type. 
Ic. Porphyritic olivine, but not felspar; groundma.ss suh-f,-, „ 
ophitic. jGallaston Type. 
2. Olivine -Basalts 
2ff. Porphyritic olivine, augite and felspar ; groundinass off Lion’s Haunch Type, 
felspar-laths imbedded in granules of augite. / (See Fig. 207.) 
Porphyritic olivine and augite ; groundmass of felspar- i 
laths imbedded in granules of augite. More rarely the ! p ■ i i.i ^ 
groundmass is made of idioinorphic augite imbedded in j 
lelspar-substance. j 
Porphyritic olivine abundant, augite much less common, J 
and felspar very rare or absent ; groundmass with ^ 
granular or idioinorphic augite (one of the most common j ^ meny j pe. 
types). j 
2(7. Porphyritic olivine more common than augite ; ground-] 
mass of granules of augite set amongst lath-like felsjiars -Picrite Type, 
which are much fewer in number than in 2c. j 
2s. Porphyritic olivine more common than augite ; ground-] 
mass of idiomor]ihic augite imbedded in felspathic -Limburgite Type, 
material which is not abundant. ) 
Porphyritic olivine and felspar, without augite ; ground-] . 
mass of granular or idinninrubic. niimlo toUI. 
shaped felspars. 
2 /). 
2c. 
a/- 
idiomorphie augite, with lath- _ 
^ (For analysis see p. 379). 
II. The Non-olivine-be.vrijig Serie.s 
3. Olivine -free Dolerites 
Felspar, augite, magnetite in coarse-grained aggregate usually ophitic or sub- 
ophitic ; groundmass not plentiful. 
3(1. Groundmass absent .... Ophitic Type. 
36. Groundmass micropegmatitio . . . Patlio Tvpe. 
3c. Groundmass an unstriated felspar (not orthoclase) and] 
occasionally some interstitial altered glass or a little -Burntisland Sill Type, 
quartz. I 
4. Doleritic Basalts 
Felspar, augite and magnetite in coarse-grained aggregate ; groundmass rather 
more plentiful and often in large patclies. 
4ft. Felspar and augite, related siib-ophitically where together,'! 
but augite showing crystalline contours in contact with | _ 
the groundmass ; some interstitial quartz and unstriated Type, 
felspar. j 
