o48 Day and Sos/nan — Melting Points of Minerals. 



TABLE II. — Approximate Temjieratit re Delermiiittlions. 



Substance 



Cristobalite 

 (from quartz) 



Quartz 



Eutectic* 

 between cristo- 

 balite and 

 sillimanite 



Eutectic between 

 corundum and 

 sillimauite 



Magnesium 

 metasilicate 



I' ula 



Si0 2 



Si0 2 



/3-Caleium 

 metasilicate, 

 (Wollastonite) 



Calcium 



orthosilicate 

 Calcium 



orthosilicate 



Tricalcium 

 silicate 



Eutectic of 

 spinel and 

 perielase 



Albite 



Oligoclase- 

 Andesine 



Microeline 



Andalusite 



Cyanite or 

 disthene 



e'-Magnesiurn 

 metasilicate, 

 (Enstatite) 



/^'-Magnesium 

 metasilicate, 

 monoclinic 

 amphiboleg 



y'-Magneshtm 

 metasilicate, 

 orthorbombic 

 ampbibole§ 



SiO a 80£ 

 AloSiOr, 



A1 2 3 3% 

 AloSi0 6 



MgSiOa 



97% 



CaSi0 3 



Ca 2 Si0 4 

 Ca 2 Si0 4 



!3CaO.Si0 2 



MgO.Al 2 3 and 

 MgO 



|NaAlSi 3 O e 



Albite 3 

 Anorthitei 



!KAlSi 3 8 



Al 2 Si0 5 



Al 2 Si0 6 



MgSi0 3 



MgSi0 3 



MgSi0 3 



Transformation 



Melting 



Inversion to 

 cristobalite 



Melting 



Melting 



Inversion a to 



(3 (clino- 



enstatite), and 



reverse 

 Inversion to 



a-CaSiO s 



(pseudo- 



wollastonite), 



and reverse 

 Inversion a to 



P and reverse 

 Inversion f3 to 



y and reverse 

 Formation of 2 



phases by 



dissociation 



Tempera- 

 ture 



About 

 1600 



Above 

 800 



A little 

 below 

 1600 



About 

 1810 



About 

 1375 



Melting 



Change to 

 sillimanite 



Change from 

 unstable form 

 to /3-MgSi0 3 

 (clino-enstatite) 



1190 



1420 



About 

 1900 



About 

 1950 



Below 

 1200$ 



1345+ 



Below 



1200$ 

 1300 and 



above** 

 1300 and 



above** 



1300** 



1150 and 

 above** 



1150 and 

 above** 



Observer 



Day& 

 Shepherd 

 Day & 

 Shepherd 

 Wright & 

 Larsen 



Reference 



8, 11, 19 

 (1906-7) 

 8, 11, 19 

 (1906-7) 

 39, 64 

 (1909-10) 



Shepherd 41, 65 

 & Eankin (1909-10) 



Shepherd 41, 65 

 & Eankin (1909-10) 



WhTte & i 33 * 1909 ) 



6, 32 

 (1906-9) 



Day& 8, 11, 19 

 Shepherd (1906-7) 



41, 65 

 (1909-10) 



Day & 1, 4 

 Allen (1905) 



Shepherd 41, 65 

 & Eankin (1909-10) 



Allen, 



Wright & 1 13 (1906) 



Clement 



*The eutectic compositions are given in percentages by weight of the two 

 compounds named. 



t See note (f) to Table I. 



