1892.] Mineralogy and Petrography. 3 



only in the rock of the crater and in bombs, though it was pmbal 

 more abundant during the first stages of consolidation of nearly all t 

 lavas. Melilite and biotite are also rare, and both seem to have mid. 

 gone more or less resorption. In addition to the minerals above im 

 tioned bronzite is sometimes found in the olivine h 

 lite, phillipsite, gypsum, serpentine and kaolin as alteration pmdin 

 of other minerals. The most abundant lava of the volcano is h-ueii 

 tephrite, with nepheline, leueite. plagioelase and -anidine in rami 

 proportions. A phonolite dyke was discovered at Leliraidi. as alna. 

 stated. Otherwise phonolitic material is known only as tufa. 

 Melfi occurs the unique rock, many times described as a melili 

 hauynophyre. According to the author it should 

 hauyne-melilite-nephelinedeueite-tephrite. Basanites rut the ..1<] 

 tephritic lavas in the crater of the volcano. ( Massy base was detect* 

 only in some of the lapilli. The bombs thrown out during the aeti\ 

 period of the volcano's history are either olivine bombs or agirregat* 

 of augite, biotite and hauyne. In the former the components ai 

 olivine, bronzite and biotite, the latter in micropegmatitic intergrowt! 

 with the other two. The tufas fall into two classes. In one sanidir 

 and melanite are abundant ; in the other hauyne predominates. Tl 

 first is the older, and includes the trachyte tuffs of earlier authors. ] 

 is a tephrite tufa, which sometime- contain- little rounded grains < 

 quartz. The hauyne tufa is more widely spread than the tephriti 

 varieties, and is probably connected geneticallv with the phonoliti 

 lava. 



Mineralogical News — General. — Analyses of langbanite hav- 

 ing led Flink to the complicated formula 37 Mn 5 SiO s + 10 Fe, Sb t 8 

 as expressive of its composition, Backstrom 1 has thought it worth 



tionship to other nearly allied t 



Since chlorine is evolved when the mineral is treated with hydro- 

 chloric acid, the author concludes that the manganese is principally in 

 the form of Mn 2 3 , while the remainder of the metal is present as 

 MnO. The conclusion reached is to the effect that langbanite is not 

 isomorphous with any known mineral, but is an isomorphous mixture 



