200 F. A. Genth — Contributions to Mineralogy. 



lation of the alkaline solution the alumina was precipitated by 

 ammonium hydrate. The alumina, separated in this manner, 

 after dissolving it in hydrochloric acid, and treatment of this 

 solution with sodium hydrate, did not yield a trace of glucina 

 on continuous boiling of the dilute alkaline solution. 

 The following results were obtained : 



I. Burnett County. II. Llano County. 



a b a b 



Si0 2 22-87*) 23-40*) 22-80 22-92 



A1 2 3 -. 0-28 0-33 0-31 0-29 



Ce 2 3 t) 2-65 2-76 2'66 2-85 



(Di,La) a 3 5-22 5-17 5-01 5-33 



(Y,Er) 2 3 44-35 44-65 44-45 44-30 



MnO 0-22 not det. 0-18 not det. 



FeO 13-69*) 13-58 12-93 13'03 



BeO 9-24 9-32 9'19 9'34 



MgO 0-07 0-08 0-11 not det. 



CaO 0-64 0-54 0*71 0-78 



Na 2 0-20 not det. 0-23 not det. 



K„0 -. 0-15 " " 0-12 " " 



Ignition.-. -- 0'72 " " 0-79 " " 



Insoluble in dil.HSO. not det. " " 0-93 0'92 



100-30 100-42 



Decomposed Gadolinite from Llano Co. 



Spec, grav = 3*592 



Ignition 9-30 



Quartz 1-03 



SiO„ -. 22-11 



(Ce,*Di,La,Y,Er) 2 3 39-20 



Fe 2 O s 14-53 



BeO 6-03 



MnO - . - 0-22 



CaO 5-58 



2. Cacoclasite. — At the meeting of the Mineralogical and 

 Geological Section of the Academy of Natural Sciences of 

 Philadelphia, November 26th, 1883, the late Professor H. 

 Carvill Lewis described under the provisional name "caco- 

 clasite," peculiar white and grayish-white crystals, imbedded 

 in blue cleavable calcite, associated with graphite, pyroxene, 

 wollastonite, cubical spinel, pyrrhotite, etc., at Wakefield, 

 Ottawa County, Quebec, Canada. They are nearly square 

 prisms with truncated angles, the general appearance being 



* Includes the Fe 2 3 and Si0 2 , insoluble in dilute sulphuric acid. 



f Mr. L. G-. Eakins informed me that he had found Th0 2 in the Texas gado- 

 linite. As 1 had not tested for it, I examined the eerie oxide, left from the four 

 analyses, and found it to contain 3'22 per cent of Th0 2 . 



