284 DISCUSSION. 
occurring under conditions so like ours are decided by Rosen- 
busch to be pyrope. 
Diller describes exactly similar shells around a pyrope in @ 
basic rock from Elliott Co., Ky. ‘The probability is that our 
garnet is a pyrope. 
2. An analysis of the garnet showed the composition to be— 
SiO, = 
Al,O, = 23:68 
Fe,0, ‘18 
eO 10-04 
MnO 3°76 
CaO! 8°76 
MgO 14:45 
3. I then took the table of garnets given by Dana— 
Group I. Aluminium Garnet— 
1. Grossutarire—Calcium-aluminium garnet. 
2, Pyrope—Magnesium-aluminium garnet. 
3. ALMANDITE—TIron-aluminium garnet. 
4, SpessArirE— Manganese-aluminium garnet. 
Group II. Jron Garnet— 
5, ANDRADITE. 
6. OrpiInARY GARNET. 
Group IIT. Chromium Garnet— 
7. Uvarovire. 
Our garnet cannot possibly, from the analysis, belong to Groups 
Il. or III. In Group I. we have four garnets. 
The Bingara garnet has only 
‘58%, of MgO; It is not SPESSARITE which 
has 14 to 40% MgO; 
and only 8-76 of CaO; It is not GrossuLarire which 
has 24 to 36% CaO. 
and only 10:04 of FeO, It is not Atmanpins which 
has 20 to 35% of FeO. 
1 The figures for CaO and MgO were transposed in the proofs handed © 
to the members generally. I handed corrected proofs to those more 
directly interested. 
