lOS 



Twinning, which is not known to occur with the other 

 minerals of the pyrochlore group, is found rather often with 

 endeiohte. The twins are formed according to the common 

 »spinel law", and the twins form triangular tables parallel to 

 the twinning -plane with salient angles at the sides and re- 

 entering angles at the corners. 



The mineral scratches fluorile with difficulty; its hardness 

 consequently is 4. it is of a somewhat doughy consistency, and 

 impressions may be made on it by the point of a needle. It 

 has no cleavage. The fracture is subconchoidal to splintery. 



The colour of endeiolile is a dark chocolate-brown. Only 

 in thinnest splinters is it translucent with reddish-brown colour. 

 The powder is yellowish grey. The crystal faces exhibit a 

 vitreous lustre approaching to metallic. The fresh fracture, on 

 the other hand, shows a distinct greasy histre. Microscopical 

 sections of sulficient thinness are translucent with straw-yellow 

 colour. The mineral is perfectly optically isotropic and traversed 

 by numerous irregular cracks. 



By weighing in benzole the specific gravity of the mineral 

 has been determined as 3.44 (Mauzeliusl. 



Owing to the small quantity in which the mineral has been 

 found and the diminutive size and scattered occurrence of the 

 crystals it has been attended with great difficulties to procure 

 pure material for the analysis. All the available aegirine 

 crystals on which the mineral occurred were scraped, and 

 the material thus obtained was subjected to a laborious and 

 tedious process of hand-picking with the aid of a magnifier. 

 All the pure material that could be obtained in this way, 

 amounted to 0,6176 grams. This was divided into two portions. 

 In one of these, which consisted of 0,3261 gr. , H^O and F 

 were determined. The other ingredients were determined in 

 the remainder. The analysis was performed by Mauzelius 

 and, as has already been stated, simultaneously with the analysis 

 of the clialcolamprite. Both analyses showed a loss of about 



