242 Scientific Intelligence. 



dolomitization has gone on and the percentage of magnesium 

 carbonate has increased to 16 per cent. Another point of inter- 

 est is that near the surface masses of dense solid coral rock are 

 common, farther down these are rare and between 220 and 637 

 feet they do not exist, the material resembling unconsolidated 

 coral reef sand. This difference is explained by the effect of the 

 more complete solution and removal of the original aragonite. 

 When the original rock consisted chiefly of calcite this has been 

 less affected by solvent action and the rock is sufficiently coherent 

 to yield more or less solid cores; when aragonite was more prom- 

 inent its removal has left the rock in a fragmental and incoherent 

 condition. 



A marked change begins with the core at 63 S feet ; here a large 

 percentage of magnesium carbonate is found, making as before 

 stated a maximum of 43 per cent at 950 feet, and with the ex-, 

 ceptions mentioned on p. 240, this condition is maintained to the 

 bottom mineralogically. This means that the cores consist of 

 dolomite, in many cases in the form of distinct rhombohedral 

 crystals, while recognizable calcite has largely or completely 

 disappeared. A feature of the lower cores (from 815 feet down) 

 is the presence of fibrous deposits gradually increasing in relative 

 amount ; at first this consists entirely of calcite, at greater depths 

 of alternate layers of calcite and dolomite; in one case (1090 

 feet) five such layers were observed. Many interesting variations 

 are noted in the microscopic sections in the appearance of the 

 dolomite and calcite and their relations to each other and to the 

 original organisms. These are clearly described and in addition 

 are distinctly presented to the eye in the admirable series of 

 figures, all of which deserve to be carefully studied. Enough 

 has been said, however, to indicate the general, conclusions 

 arrive^ at and to show that this unique investigation serves to 

 throw much light on some of the most difficult problems in con- 

 nection with the history of the coral reef. 



4. Brief notices of sotne recently described Minerals. — 

 Bakerite is a new borosilicate of calcium described by W. B. 

 Giles from the mines of the Borax Consolidated Company in the 

 Mohave desert, 16 miles northeast of Daggett, San Bernardino 

 county, California. It occurs in white, amorphous masses form- 

 ing veins and nodules of considerable size. In appearance it 

 resembles unglazed porcelain or fine-grained marble ; occasion- 

 ally it has a faint greenish tinge. Hardness = 4*5, specific grav- 

 ity 2*V3. An analysis yielded the following results : 

 B 2 3 27'74 Si0 2 28-45 Ca034'88 H 2 O8'30 Al 2 O 3 ,Fe 2 O 3 0-63 = 100. 



From this the formula is calculated 6Si0 2 . 5B 2 3 . 8CaO . 6H 2 0. 

 The mineral is named after Mr. R. C. Baker, a director of the 

 company. It is noted that howlite also occurs in large quanti- 

 ties in the same mines. — Min. Mag., xiii, 353. 



Erikite is a new species from the nephelite-syenite of Julian- 

 ehaab, Greenland, described by O. B. Boggild. It occurs in 

 orthorhombic crystals, sometimes highly modified, of a yellowish 



