THE ANALCITE BASALTS OF SARDINIA 743 



side of a small stream just north of Scano, a village on the north- 

 eastern flank of Monte Ferru. The basalt here overHes a flow of 

 the ordinary gray trachyte of the Sennariolo type, the trachyte 

 resting on white tuffs. Below these are tertiary marls. To the 

 south of Scano is another flow, possibly connected with that to the 

 north. This forms a ridge known as Binzale Prunu, which extends 

 in a southeast direction for about 2 km. and shows three summits, 

 called Monti Columbargiu, Martu, and Lepere. I collected lavas 

 from the Scano flow, and from that of Binzale Prunu along the 

 road between Scano and Cuglieri below Monte Columbargiu, and 

 at a quarry below Monte Martu called Cava Tuvamurtas. Similar 

 basalts were also collected at a small cone west of Bonorva, a small 

 town east of Pozzo Maggiore, which apparently belongs to the 

 closing phase of the last period of small cones in Sardinia. At a 

 locaHty called Ghizo, to the west of Monte Urtigu, the culminating 

 point of Monte Ferru, there is a small exposure of a similar rock 

 containing many copper-colored biotite tables. The color of these 

 biotite crystals makes the peasants believe that the rock is an ore 

 of copper, and a peasant whom I met near by told me about a King 

 Mastino, a sort of Bergkonig, to whom all the copper belongs. It 

 is supposed that this king lives beneath the earth and has cast a 

 spell upon the copper ore so that men cannot extract the copper 

 from it. 



Megascopic characters. — -These lavas are all very dense, compact, 

 and aphanitic. Apart from nodules of olivine and augite, to be 

 described presently, the Scano flow shows few phenocrysts, a few 

 small crystals of augite and olivine and very sparing biotites being 

 the only ones visible. This lava is a rather darkish gray. The 

 lava of Bonorva, which also carries olivine nodules, much resembles 

 this except that there is no biotite. The lava flow of Binzale 

 Prunu is almost black, quite aphanitic, though with alteration it 

 assumes a brownish or even reddish color. In this are many tables 

 of a bronzy biotite which are smaller but more numerous in the 

 lava from the quarry, but larger and less numerous in that from 

 Monte Columbargiu. The tables of this biotite are all a light 

 chestnut brown, but when altered have a red color and a luster 

 resembling that of copper. Dr. Merwin found that the angle 



