Geology and Natural History. 183 



Minas Geraes, Brazil. The na,me fava is given locally to spher- 

 ical or bean-shaped rolled masses of some heavy minerals found 

 in the diamond washings and regarded as a good indication of 

 the presence of the gem. They are for the most part brown or 

 red in color, less often white. Early investigations of them have 

 been made by Damour, Gorceix and others. Hussak has identi- 

 fied among the favas, a barium-aluminium phosphate to which 

 he gives the name gorceixite. The color is light- to dark-brown 

 and the structure like jasper ; hardness = 6 ; specific gravity 

 3'04-3-]2. An analysis by G. Florence, after the deduction of 

 SiO s , Ti0 2 , Fe a O„ gave : 



P 2 5 AI0O3 BaO CaO CeO H 2 



24-48 37-68 16-60 3-82 1-67 15-74=100 



For this the composition Ba0.2Al o 3 .P 2 6 .5H 2 0, is calculated. 



The name harttite, after Prof. Fred. Hartt, is given to favas of 

 a flesh-red to yellow or white color; hardness about 5'5, sp. 

 gravity 3*1 4-3*21. Microscopic examination showed a micro- 

 crystalline structure and suggested hexagonal crystallization. 

 Analysis by G. Florence gave : 



P 2 6 AI0O3 S0 3 SrO CaO H 2 



21-64 34-40 11-78 17-17 2-19 12-81 = 100 



The calculated composition is Sr(Ca)0.2Al 2 3 .P 2 5 .S0 3 .5H 2 ; 

 this shows a close resemblance to svanbergite. Other favas 

 proved to be phosphates of aluminium and lead closely similar to 

 plumbogummite. — Min.Petr. Mitth., xxv, 335, 1906. 



7. Chiastolite from Bimbowrie, South Australia. — The argil- 

 laceous schists of Mt. Howden, ten miles north of Bimbowrie, 

 South Australia, have furnished some remarkable specimens of 

 chiastolite of unusual size and showing some new features for the 

 mineral. An account of them was published by C. Anderson in 

 the Records of the Austi'alian Museum, vol.iv, pp. 298-302. The 

 locality has been specially developed by Mr. G. R. Howden, who 

 has furnished specimens to the Australian Museum and also to the 

 Yale Museum at New Haven. 



The chiastolite occurs either embedded in argillaceous schist 

 or as rolled pebbles with quartz, jasper, etc. Some of the com- 

 mon forms show a simple cross of nearly pure mineral with also 

 a light-colored core, surrounded by four dark lines, forming a 

 rectangle when cut normal and a lozenge when cut oblique to 

 the axis. These specimens measure up to 2^ inches in cross- 

 section. 



A very peculiar form is that called " fish crystals," the struc- 

 ture of which is best revealed in weathered specimens. These 

 have an elongated and flattened form, the length often reaching 

 five or six inches. They have a central core with projections on 

 opposite sides (see fig. 1) ; these show a peculiar series of grooves 

 and ridges, curved on either side of the axis and in opposite 

 directions. In some cases, also, the longer arms are slightly bent 

 in opposite directions. This deformation is well marked when 

 the grooving is most apparent. 



