29:
440:
Fallout ash beds in sedimentary rock of the western United States have been classified in part by whether sanidine phenocrysts are present and, if present, whether they are sodium-enriched. W-type rhyolite ash beds contain sodium-poor sanidine; G-type rhyolite ash beds contain sodium-rich sanidine;
583:
At elevated temperature, a complete solid solution exists between sanidine and albite. Rapid cooling of the sanidine freezes the composition, though most sanidine is cryptoperthitic, showing separate layers of low-sodium sanidine and albite at a sub-micron scale that can be detected only by
495:. Calcium and sodium substitute for potassium (with concurrent substitution of additional aluminum for silicon, in the case of calcium) while ferric iron substitutes for aluminum. A typical natural composition is:
648:
o sites, breaking the monoclinic symmetry and producing triclinic microcline. Each transition requires exchange of ions between tetrahedral sites, which takes place at measurable rates only at high temperature.
405:
Due to the high temperature and rapid quenching, sanidine can contain more sodium in its structure than the two polymorphs that equilibrated at lower temperatures. Sanidine and high
673:
temperature of 990 °C, which defines the "granite" eutectic. The temperature at which granite begins to melt is lowered by several hundred degrees by the presence of water.
600:
The crystal structure of ideal potassium feldspar has four sets of tetrahedral sites, each capable of accepting either an aluminum or a silicon ion. These are labeled the T
644:
m sites. The resulting orthoclase crystal retains monoclinic symmetry but with different crystal axis lengths. Further cooling causes the aluminum to concentrate in the T
742:
441:
and dacite fallout ash beds frequently lack sanidine. Because of their high potassium content, sanidine phenocrysts are also very useful for
996:
971:
936:
911:
94:
391:
886:
861:
824:
799:
219:
252:
991:
632:
m sites. This produces a crystal with monoclinic symmetry. With slow cooling, the aluminum becomes concentrated in the T
104:
84:
585:
209:
199:
616:
m sites. In sanidine, the aluminum and silicon are distributed randomly among all four sites, and the T
749:
703:
589:
418:
242:
232:
721:
442:
189:
986:
967:
932:
907:
882:
857:
820:
795:
417:. Exsolution of an albite phase does occur; resulting cryptoperthite can best be observed in
711:
280:
262:
179:
62:
446:
476:
707:
410:
114:
38:
980:
725:
364:
312:
169:
126:
429:
In addition to its presence in the groundmass of felsic rocks, sanidine is a common
414:
34:
777:
144:
434:
430:
395:
388:
384:
380:
135:
119:
931:(2nd ed.). Cambridge, UK: Cambridge University Press. pp. 207–208.
666:
492:
399:
346:
41:, France. Size 5 cm × 4.5 cm (2.0 in × 1.8 in)
743:"The New IMA List of Minerals – A Work in Progress – Updated: March 2014"
670:
376:
372:
368:
349:
322:
55:
716:
691:
658:
488:
465:
765:
662:
484:
458:
406:
361:
28:
819:(2nd ed.). Honolulu: University of Hawaii Press. p. 128.
657:
Pure sanidine melts incongruently at 1150 °C, yielding solid
457:
Although the ideal composition of sanidine is 64.76 wt%
881:(21st ed.). New York: Wiley. pp. 535–536, 541.
394:
stable at lower temperatures. At yet lower temperatures,
856:. San Francisco, CA: Freeman, Cooper. pp. 104–111.
906:. New York: Oxford University Press. pp. 210–211.
437:. Trachyte consists largely of fine-grained sanidine.
877:Klein, Cornelis; Hurlbut, Cornelius S. Jr. (1993).
333:
321:
311:
279:
271:
261:
251:
241:
231:
218:
208:
198:
188:
178:
168:
160:
155:
143:
125:
113:
103:
93:
83:
61:
51:
46:
21:
636:sites but remains randomly distributed between T
929:Principles of igneous and metamorphic petrology
624:m are mirror images of each other, as are the T
962:Hurlbut, Cornelius S.; Klein, Cornelis, 1985,
951:
778:http://www.webmineral.com/data/Sanidine.shtml
413:series with intermediate compositions termed
8:
927:Philpotts, Anthony R.; Ague, Jay J. (2009).
483:, natural sanidine incorporates significant
402:polymorph of potassium feldspar, is stable.
817:Volcanoes in the Sea: The Geology of Hawaii
879:Manual of Mineralogy (after James D. Dana)
27:
715:
497:
794:. Berlin: Springer-Verlag. p. 22.
682:
661:and liquid. A mixture of sanidine with
360:). Sanidine is found most typically in
839:
433:in rhyolites and, to a lesser extent,
18:
737:
735:
7:
692:"IMA–CNMNC approved mineral symbols"
766:http://www.mindat.org/min-3521.html
14:
174:Tabular crystals, may be acicular
345:is the high temperature form of
852:McBirney, Alexander R. (1984).
379:. Sanidine crystallizes in the
653:Sanidine and genesis of magmas
1:
815:Macdonald, Gordon A. (1983).
352:with a general formula K(AlSi
445:of rhyolite ash beds by the
237:Vitreous, pearly on cleavage
790:Fisher, Richard V. (1984).
1015:
997:Minerals in space group 12
904:Introduction to mineralogy
902:Nesse, William D. (2000).
596:Order-disorder transitions
257:Transparent to translucent
16:Form of potassium feldspar
952:Philpotts & Ague 2009
194:{001} perfect, {010} good
26:
327:Measured: 18°–42° (low);
184:Carlsbad twinning common
696:Mineralogical Magazine
586:X-ray crystallography
475:, and 16.72 wt%
95:Strunz classification
37:, Monts-Dore massif,
964:Manual of Mineralogy
992:Monoclinic minerals
966:, 20th ed., Wiley,
842:, pp. 355–356.
717:10.1180/mgm.2021.43
708:2021MinM...85..291W
690:Warr, L.N. (2021).
590:electron microscope
419:electron microprobe
105:Dana classification
755:on March 25, 2014.
443:radiometric dating
272:Optical properties
164:Colorless to white
854:Igneous Petrology
792:Pyroclastic rocks
581:
580:
464:, 18.32 wt%
340:
339:
139:
1004:
955:
949:
943:
942:
924:
918:
917:
899:
893:
892:
874:
868:
867:
849:
843:
837:
831:
830:
812:
806:
805:
787:
781:
775:
769:
763:
757:
756:
754:
748:. Archived from
747:
739:
730:
729:
719:
687:
498:
383:crystal system.
281:Refractive index
263:Specific gravity
224:
133:
131:Prismatic (2/m)
68:
67:(repeating unit)
31:
19:
1014:
1013:
1007:
1006:
1005:
1003:
1002:
1001:
977:
976:
959:
958:
950:
946:
939:
926:
925:
921:
914:
901:
900:
896:
889:
876:
875:
871:
864:
851:
850:
846:
838:
834:
827:
814:
813:
809:
802:
789:
788:
784:
780:Webmineral data
776:
772:
764:
760:
752:
745:
741:
740:
733:
689:
688:
684:
679:
665:in the form of
655:
647:
643:
639:
635:
631:
627:
623:
619:
615:
611:
607:
603:
598:
573:
561:
542:
538:
527:
523:
512:
480:
473:
469:
462:
455:
427:
359:
355:
328:
306:
300:
298:
292:
290:
222:
132:
78:
74:
66:
65:
42:
17:
12:
11:
5:
1012:
1011:
1008:
1000:
999:
994:
989:
979:
978:
975:
974:
957:
956:
954:, p. 252.
944:
937:
919:
912:
894:
887:
869:
862:
844:
832:
825:
807:
800:
782:
770:
758:
731:
702:(3): 291–320.
681:
680:
678:
675:
654:
651:
645:
641:
637:
633:
629:
625:
621:
617:
613:
609:
605:
601:
597:
594:
579:
578:
575:
571:
567:
566:
563:
559:
555:
554:
551:
547:
546:
543:
540:
536:
532:
531:
528:
525:
521:
517:
516:
513:
510:
506:
505:
504:Weight %
502:
478:
471:
467:
460:
454:
451:
426:
423:
411:solid solution
365:volcanic rocks
357:
353:
338:
337:
335:
331:
330:
329:15°–63° (high)
325:
319:
318:
315:
309:
308:
304:
299:= 1.523–1.530
296:
291:= 1.518–1.525
288:
283:
277:
276:
273:
269:
268:
265:
259:
258:
255:
249:
248:
245:
239:
238:
235:
229:
228:
225:
216:
215:
212:
206:
205:
202:
196:
195:
192:
186:
185:
182:
176:
175:
172:
166:
165:
162:
158:
157:
156:Identification
153:
152:
147:
141:
140:
129:
123:
122:
117:
115:Crystal system
111:
110:
107:
101:
100:
97:
91:
90:
87:
81:
80:
76:
72:
69:
59:
58:
53:
49:
48:
44:
43:
33:Sanidine from
32:
24:
23:
15:
13:
10:
9:
6:
4:
3:
2:
1010:
1009:
998:
995:
993:
990:
988:
985:
984:
982:
973:
972:0-471-80580-7
969:
965:
961:
960:
953:
948:
945:
940:
938:9780521880060
934:
930:
923:
920:
915:
913:9780195106916
909:
905:
898:
895:
890:
884:
880:
873:
870:
865:
859:
855:
848:
845:
841:
836:
833:
828:
822:
818:
811:
808:
803:
797:
793:
786:
783:
779:
774:
771:
767:
762:
759:
751:
744:
738:
736:
732:
727:
723:
718:
713:
709:
705:
701:
697:
693:
686:
683:
676:
674:
672:
668:
664:
660:
652:
650:
595:
593:
591:
587:
576:
569:
568:
564:
557:
556:
552:
549:
548:
544:
534:
533:
529:
519:
518:
514:
508:
507:
503:
500:
499:
496:
494:
490:
486:
482:
474:
463:
452:
450:
448:
444:
438:
436:
432:
424:
422:
420:
416:
412:
409:constitute a
408:
403:
401:
397:
393:
390:
386:
382:
378:
374:
370:
366:
363:
351:
348:
344:
336:
332:
326:
324:
320:
316:
314:
313:Birefringence
310:
307:= 1.525–1.531
303:
295:
287:
284:
282:
278:
274:
270:
266:
264:
260:
256:
254:
250:
246:
244:
240:
236:
234:
230:
226:
221:
217:
213:
211:
207:
203:
201:
197:
193:
191:
187:
183:
181:
177:
173:
171:
170:Crystal habit
167:
163:
159:
154:
151:
148:
146:
142:
137:
130:
128:
127:Crystal class
124:
121:
118:
116:
112:
108:
106:
102:
98:
96:
92:
88:
86:
82:
70:
64:
60:
57:
54:
50:
45:
40:
36:
30:
25:
20:
963:
947:
928:
922:
903:
897:
878:
872:
853:
847:
835:
816:
810:
791:
785:
773:
761:
750:the original
699:
695:
685:
656:
599:
582:
456:
439:
428:
415:anorthoclase
404:
342:
341:
301:
293:
285:
149:
35:Puy de Sancy
840:Fisher 1984
669:melts at a
453:Composition
447:K–Ar dating
435:rhyodacites
275:Biaxial (−)
253:Diaphaneity
145:Space group
109:76.01.01.02
39:Puy-de-Dôme
981:Categories
888:047157452X
863:0877353239
826:0824808320
801:3540127569
768:Mindat.org
677:References
501:Component
431:phenocryst
425:Occurrence
396:microcline
389:monoclinic
385:Orthoclase
381:monoclinic
334:References
220:Mohs scale
136:H-M symbol
120:Monoclinic
85:IMA symbol
726:235729616
667:tridymite
592:methods.
493:iron(III)
400:triclinic
392:polymorph
347:potassium
317:δ = 0.007
987:Feldspar
671:eutectic
612:o, and T
449:method.
421:images.
377:trachyte
373:rhyolite
369:obsidian
367:such as
350:feldspar
343:Sanidine
323:2V angle
223:hardness
210:Tenacity
200:Fracture
190:Cleavage
180:Twinning
56:Feldspar
52:Category
22:Sanidine
704:Bibcode
659:leucite
640:o and T
628:o and T
620:o and T
489:calcium
214:Brittle
99:9.FA.30
63:Formula
47:General
970:
935:
910:
885:
860:
823:
798:
724:
663:silica
577:10.05
530:19.92
515:64.03
491:, and
485:sodium
407:albite
362:felsic
243:Streak
233:Luster
204:Uneven
134:(same
71:K(AlSi
753:(PDF)
746:(PDF)
722:S2CID
565:4.57
553:0.45
545:0.62
387:is a
247:White
161:Color
968:ISBN
933:ISBN
908:ISBN
883:ISBN
858:ISBN
821:ISBN
796:ISBN
608:m, T
604:o, T
550:CaO
398:, a
375:and
267:2.52
150:C2/m
712:doi
588:or
509:SiO
459:SiO
983::
734:^
720:.
710:.
700:85
698:.
694:.
574:O
562:O
558:Na
535:Fe
520:Al
487:,
466:Al
371:,
89:Sa
941:.
916:.
891:.
866:.
829:.
804:.
728:.
714::
706::
646:1
642:1
638:1
634:1
630:2
626:2
622:1
618:1
614:2
610:2
606:1
602:1
572:2
570:K
560:2
541:3
539:O
537:2
526:3
524:O
522:2
511:2
481:O
479:2
477:K
472:3
470:O
468:s
461:2
358:8
356:O
354:3
305:γ
302:n
297:β
294:n
289:α
286:n
227:6
138:)
79:)
77:8
75:O
73:3
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