202 



PHYSIOGRAPHY. 



Spinel. 



3. It occurs, implanted upon Stilbite from Faroe. 



4. Its properties as given above, do not appear to justify the formation 

 of a new species. 



SPHERULITE. (See Pitchstone.) 



SPINEL. Do decahedral Corundum. MOHS. 

 Primary form. Regular octahedron. 

 Secondary forms. 



1. 2. 3. 



Primary with edges Primary with edg- Primary with edges 



truncated. 

 Hamburg, (N. J.) 



es bevelled. 

 Vesuvius. 



4. Fig. 416. 



and angles truncated. 

 Hamburg, (N. J.) 



Hamburg, (N. J.) 



5. 



Primary with edges replaced by three planes, 



and angles by four planes resting 



on the primary faces. 



Vesuvius. 



Cleavage parallel with the primary form difficult. Frac- 

 ture conchoidal. Surface smooth, the faces t sometimes 

 striated parallel to the edges of combination with the octa- 

 hedron. 



Lustre vitreous. Color red, passing into blue and green, 

 also into yellow, brown and black. Sometimes nearly 



