46 



THE CANADIAN NATURALIST. 



[Vol. 



IX. 



change has come over it that has resulted in a molecular trans- 

 formation, affecting both the crystalline character and the density. 

 Saussurite appears to cover a group of minerals, like feldspar. 

 One kind is between anorthite and zoisite in composition, though 

 diiFerino; from both in the soda and mai^nesia. and from all feld- 

 spars in its not having the feldspar-ratio between the silica and 

 soda. A second has the composition of labradorite ; and a third 

 the composition nearly of oligoclase. A fourth, from Corsica, 

 analysed by Boulanger, is a lime-alumina silicate, like anorthite 

 and zoisite. The saussurite group, with density between 2-9 and 

 3*4, runs nearly parallel with the feldspar group. The first is 

 Saussurite, Th. de Saussure having named thus the Lake Geneva 

 variety, after his father, in 1806; the third is Jddeite ; and the 

 second may be called, from one of its localities, Genevrite, 



The following are the analyses of three prominent kinds, and 

 of normal anorthite, labradorite and oligoclase. 



Si2 AI2O3 FeoOs FeO 

 I.L.Geneva 43-59 'Zl-l'Z 2-61 



2. L. Geneva 45-34 30-28 1-37 



3. Schwartzwald 42-64 31-00 2-40 



II. 



4. Mt. Genevre 49-73 29-65 0-85 



5. Silesia 5084 26-00 2-73 



6. Silesia 51*76 26 82 1-77 



7. Unst 52-21 29-64 0-48 



8. Unst 53-14 29-99 0-25 



9. Durance 56-12 17-40 7-79 



III. 



10. Jadeite, China, 59-17 22-58 1-56 



11. " Switz 58-89 22-40 1-66 



12. " " 58-28 21-86 2-41 



13. Normal anorthite . . 43-1 36-9 



14. Normal labradorite. 52'9 30.3 



15. Normal oligoclase . . 61*9 24-1 



Specific gravity of 1, 3-227 ; of 2, 3-3-3-4 ; of 3. 3-16: of 4, 3-10 ; of 5, 2-998: of 

 6, 2.74 ; of 7. 2.95 : of 8, 2 954 : of 9. 2.923 : of 10, 333-3.35 : of 11, 3 32 ,- of anorthite, 

 2-66-2-763; of labradorite. 2 67-2-76; of oligoclase. 2-5<i-2-72. 



To No. 9, add Cr203 (>-51. and to 11, ZnO 0.73. Nos. 10 to 12 are only known 

 worked into ornaments, biit the kind may yet be found in the Alps. No. 5 has 

 the specific gravity of labradorite fnd was therefore that species, a mineral that 

 would be present where the crystallization took place without, or with only par- 

 tially, the conditions needed to produce saussurite. No. 9 is of the globules of 

 the " Variolite of Durance." a rock associated with euphotide. 



Boulanger's saussurite. from Corsica, is near zoinite in composition and density 

 (G.=3-18), as stated by T. S. Hunt, who referred all true saussurite to zoisite 

 confirming his view by his analysis above), and the part near labradorite to 

 that of feldspar. Damour obtained for yac/e^Ve the ratio 1:2:6. 



