Fig. 3. — Curves showing the effect of sampling by slides 

 from granite, Dyers Quarry, Meledor. 



\T - ImcT or SAMPLING. 



Number of 5 I ides in Sample 



Table II. — Standard Deviations oe Mineral Percentages calcu- 

 lated from the Volumes in Table I (p. 549). 



Number of slides 



Mean. 



Standard deviation 



(tvith 



reference to mean). 



8 



1 



2 



3 



4 



5 



6 



7 



Mineral. 



32-2 







2-6 



19 



1-5 



1-3 



0-6 



Quartz 



5-8 



35 



Orthoclase 



41-1 



7-5 4-9 



3 o 



2-8 



2-0 



1-9 



12 



Plagioclase 



15-8 



3-0 1-9 



1-6 



l-o 



0-9 



07 



0-4 



Mica 



4-3 



1-5 | 1-0 



0-8 



0-6 



0-4 



0-36 



0-26 



Accessories 



0-2 



0-1 





I 



1 

 1 



