168 DOMAIN X. 



tars, sarcophages, made of black stones, which 

 have all the characters attributed to the ancient 

 basalts, and which have preserved that name ; and 

 I can say, with positive certainty, that none of 

 them is volcanic." Dolomieu then proceeds to 

 state that some of them are siderite, or massive 

 hornblende ; but the most common are a kind of 

 granite, in which the siderite so predominates 

 that the mass appears black, though it be asso- 

 ciated with a white felspar, of which the grains 

 are so small, or so interlaced with the scales of 

 siderite, that it is difficult to discern them ; espe- 

 cially as the felspar itself sometimes appears 

 black, because it is transparent. He adds that 

 it happens sometimes that a greater quantity of 

 felspar imparts to the rock the appearance of a 

 real granite; that is, as Daubuisson observes, a 

 real grunstein. 



This passage of Basaltin into the real Basalt 

 of the ancients, is one of the most remarkable in 

 Geology; and particularly interesting to the 

 accurate and scientific observer. It seems, how- 

 ever, to be somewhat surprising that, while these 

 substances are often found to coalesce, the 

 Egyptians did not prefer the close grained and 

 uniform basaltin to their coarser basalt. Siderite 

 is also found in Mount Sinai, and perhaps in the 

 eastern chain between Egypt and the Red Sea j 



