ILLUSTRATIONS. 



FIGURE 1. A, Orthographic projection of crystals with similar combinations, in 

 parallel grouping, joined by the a (100) faces; B, Same with dis- 



similar combinations ........................................... 41 



2. Superposed crystals, joined by the (001) faces .................... 41 



3. Long, narrow, wedge-shaped crystal of habit 1 ..................... 57 



4. Short, prismatic, somewhat flattened crystal of habit 2 ............ 57 



5. Tabular crystal of habit 3 ......................................... 57 



6. Cubic crystal of habit 4 .......................................... 57 



7. Rhombic crystal of habit 5 ...................................... 57 



8. Cleavage pieces of crystals ........................................ 58 



9. Striations on wedge-shaped crystals of habit 1 ...................... 59 



10. Crystal No. 4, wedge-shaped habit ............................... 59 



11 . Peculiar shape of wedge-shaped habit caused by cleavage .......... 59 



12. Crystal of short prismatic, somewhat flattened habit .............. 59 



13. Crystal of rhombic habit, nearly equidimensional .................. 59 



14. Contact twin on (02~3) ............................................ 63 



15. Contact twin on (023) ............................................ 63 



16. Line of contact of two contact twins .............................. 63 



17. Penetration twin on (02~3) ........................................ 64 



18. Penetration twin on (023) ........................................ 64 



19. Crystal No. 29 .................................................. 64 



20. Crystal No. 32 .................................................. 64 



21. Crystal No. 33 .................................................. 64 



22. Crystal No. 5 ................................................... 66 



23. Crystal No. 6 ................................................... 66 



24. Crystal No. 9 ................................................... 66 



25. Crystal No. 13 .................................................. 66 



26. Crystal No. 16 .................................................. 67 



27. Crystal No. 17 .................................................. 67 



28. Crystal No. 18 .................................................. 67 



29. Crystal No. 19 .......................... ........................ 67 



30. Crystal No. 20 .................................................. 68 



31. Crystal No. 36 .................................................. 68 



32. Cubic crystal ................................................... 68 



33. Rhombic crystal ................................................ 68 



34. Crystal No. 26 .................................................. 68 



35. Gnomonic projection of forms of the wolframite group ............. 70 



