138 THE ROMAN COMAGMATIC REGION. 
SACCAL ALBAN05E. III. 8. 2. 2. 
Megascopic characters. Very dark gray, compact, aphyric, or with very rare phenocrysts 
of augite and leucite, aphanitic. 
Microscopic characters. Holocrystalline, microporphyritic. Microphenocrysts : about 20 
per cent, augite. Microgroundmass : about 80 per cent, leucite, augite, anorthite, nephelite. 
olivine, magnetite, apatite, usually melilite. 
Anorthite. Four to 10 per cent, anhedral, part as very small prisms, part interstitial, 
sometimes difficult to detect. 
Leucite. About 35 per cent, 0.03 to o. 10 mm., anhedral, equant, usually round sections* 
sometimes irregular, clear, inclusions few. 
Nephelite. About 5 per cent, anhedral, interstitial cement. 
Augite. Microphenocrysts: about 20 per cent, 0.2 to 0.5 mm., subhedral to anhedral, 
prismatic, often fragmentary, pale greenish-gray, sometimes zonal. Microgroundmass: about 
30 per cent, 0.02 to o. 2 mm., anhedral, prismatic and equant, very pale greenish-gray. 
Olivine. 4 to o per cent, 0.05 to o. 10 mm., anhedral to subhedral, equant, colorless. 
Melilite. o to 5 per cent, anhedral, as formless, interstitial areas, yellowish. 
Magnetite. About 2 per cent, 0.02 to 0.05 mm., anhedral, equant. 
Apatite. About i per cent, 0.03 to o. 10 mm., subhedral, prismatic. 
Chemical composition and norm as on p. 135. 
Type specimens from Pofi and Ticchiena, Hernican District. 
HI. 8. 2. 2. Boval Albanose | Leucitite, Bove Type, Cecilite . 
Megascopic characters. This type does not differ in the hand specimen, to any 
marked extent, from those just described. The rocks are dense, very dark gray, in 
this more like the hernical type, and are aphanitic. They are for the most part 
entirely aphyric, but may carry very rare phenocrysts of leucite or augite, as in the 
other cases. Some of them, as specimens from Capo di Bove, show a peculiar, very 
faint mottled appearance, in patches of very slightly greenish-gray mingled with the 
general dark gray. This has been noticed in other melilite rocks, as well as in 
more ordinary basalts, and seems to be due to incipient weathering. 
Microscopic characters. This type is wholly holocrystalline, and with a peculiar 
fabric which resembles the clathrate described above, but differs in the greater 
thickness of the spaces between the round leucite spots. 
Small (0.05 to 0.20), round leucites are abundant, making up about one-half of 
the rock. Many of them are subhedral, showing some crystal planes, while others 
are quite anhedral and with round outlines. They very commonly carry small, 
mostly black, inclusions, which are arranged radially or as circular lines of dots. 
Birefringence is rather weak but unmistakable. 
Between these are the other constituents. There is a good deal of augite, of 
the usual pale-gray color, which is largely in formless, interstitial masses, but occa- 
sionally subhedrally prismatic. This constitutes about one-quarter of the rock. 
Melilite is also present in very considerable amount, but less than the augite, in 
similar interstitial areas, usually poikilitic. The mineral is of a very pale yellowish- 
gray, with high relief, shows the usual blue-gray color between crossed nicols, 
and has often the well-known "pflock" structure. There are also similar areas of 
