143:
132:
124:
63:
occurs at the base of the oxidized portion of an ore deposit. Metals that have been leached from the oxidized ore are carried downward by percolating groundwater, and react with hypogene sulfides at the supergene-hypogene boundary. The reaction produces secondary sulfides with metal contents higher
493:
The net effect of these supergene processes is to move metal ions from the leached zone to the enriched zone, increasing the concentration there to levels higher than in the unmodified primary zone below, possibly producing a deposit worth mining.
153:
Distinct zones of supergene processes can be identified at various depths. From the surface down they are the gossan cap, leached zone, oxidized zone, water table, enriched zone (supergene enriched zone) and primary zone (hypogene zone).
348:
with calcite) to produce secondary carbonates. Soluble salts continue on down, but insoluble salts are left behind in the oxidised zone where they form. Examples of insoluble salts that are commonly found in the oxidized zone include
743:
345:
107:
All such processes take place at essentially atmospheric conditions, around room temperature (25 °C) and standard
112:
864:
353:
694:
217:
108:
826:
325:
316:
generally are first converted to sulfates, which in turn react with primary carbonates such as
739:
667:
302:
262:
142:
815:
Field Guide to North
American Rocks and Minerals (1992) The Audubon Society. Alfred A Knopf
791:
The
Encyclopedia of Gemstones and Minerals (1991). Martin Holden. Publisher: Facts on File
663:
503:
31:
processes or enrichment are those that occur relatively near the surface as opposed to deep
313:
298:
209:
136:
131:
56:
205:
147:
36:
490:(Cu) are stable in these conditions and they are characteristic of the enriched zone.
858:
487:
213:
40:
232:), portrayed in the idealized chemical reaction below (intermediate steps omitted):
582:
514:
365:
779:
Understanding
Mineral Deposits (2000). Kula C Misra. Kluwer Academic Publishers
640:
606:
538:
445:
429:
220:
of oxidized metals. For example, groundwater commonly interacts with pyrite (FeS
197:
659:
578:
479:
69:
48:
684:
618:
614:
568:
560:
534:
475:
449:
385:
357:
337:
286:
93:
77:
189:
cap or iron hat. Prospectors use gossan as an indication of ore reserves.
123:
715:
306:
294:
174:
170:
81:
32:
655:
522:
471:
470:
that move down into this reducing environment form a zone of supergene
421:
401:
317:
52:
24:
293:. Solutions traveling downward from the leached zone react with other
632:
556:
464:
381:
201:
186:
162:
65:
185:
O), which form a porous covering over the oxidized zone known as a
453:
290:
141:
130:
122:
44:
467:
350:
16:
In geology, processes or enrichment that occur near the surface
20:
64:
than those of the primary ore. This is particularly noted in
309:, which is a characteristic product in all oxidised zones.
35:
processes. Supergene processes include the predominance of
224:) to form an oxidized iron (FeO(OH)) and sulfuric acid (H
297:
in the oxidised zone to form secondary minerals such as
59:
and redistribute the metallic ore elements. Supergene
761:
Manual of
Mineralogy (1993) Klein and Hurlbut. Wiley
277:), which oxidizes pyrite and other sulfide minerals.
521:(primary) readily alters to the secondary minerals
312:In the formation of secondary carbonates, primary
104:) are deposited by the descending surface waters.
734:Guilbert, John M. and Charles F. Park Jr (1986)
848:John Rakovan (2003) Rocks & Minerals 78:419
68:ore deposits where the copper sulfide minerals
208:. As it travels downwards it oxidizes primary
8:
146:Chalcocite pseudomorph after covellite from
698:) meaning 'born' or 'produced'. The terms
285:Above the water table the environment is
706:refer to the depth at which they occur.
254:
250:
246:
242:
238:
727:
135:Azurite and malachite on limonite from
811:
809:
807:
805:
803:
801:
799:
797:
787:
785:
775:
773:
771:
769:
767:
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753:
751:
39:circulation (i.e. water derived from
7:
844:
842:
840:
838:
502:The primary zone contains unaltered
688:meaning 'above' and the Greek root
261:An intermediate in this process is
581:ZnS (primary) alters to secondary
559:PbS (primary) alters to secondary
14:
654:If the original deposits contain
51:. The descending meteoric waters
448:the environment changes from an
682:is derived from the Latin root
639:(primary) alters to secondary
1:
828:Topic 9: Supergene enrichment
662:bearing minerals, secondary
736:The Geology of Ore Deposits
212:, concomitant with forming
881:
825:Harraz, Hassan Z. (2012),
693:
169:) has oxidised to form
55:the primary (hypogene)
683:
150:
139:
128:
127:Idealized mineral vein
145:
134:
126:
109:atmospheric pressure
57:sulfide ore minerals
510:Mineral alterations
200:contains dissolved
43:) with concomitant
831:, Tanta University
384:precipitates like
289:, and below it is
249:→ 4 FeO(OH) + 8 H
151:
140:
129:
738:, W. H. Freeman,
452:environment to a
872:
865:Economic geology
849:
846:
833:
832:
822:
816:
813:
792:
789:
780:
777:
762:
759:
746:
732:
697:
670:will be formed.
504:primary minerals
314:sulfide minerals
295:primary minerals
257:
210:sulfide minerals
880:
879:
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137:Bisbee, Arizona
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321:
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263:ferric sulfate
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229:
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206:carbon dioxide
194:
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182:
173:(FeO(OH)) and
166:
159:
156:
148:Butte, Montana
120:
117:
101:
97:
89:
85:
73:
37:meteoric water
15:
13:
10:
9:
6:
4:
3:
2:
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744:0-7167-1456-6
741:
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728:
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558:
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524:
516:
509:
507:
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497:
495:
491:
489:
488:native copper
481:
477:
473:
469:
466:
460:Enriched zone
459:
457:
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431:
423:
403:
387:
383:
367:
359:
355:
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310:
308:
304:
300:
296:
292:
288:
281:Oxidized zone
280:
278:
264:
235:
234:
233:
219:
215:
214:sulfuric acid
211:
207:
203:
199:
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157:
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149:
144:
138:
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125:
118:
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95:
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71:
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62:
58:
54:
50:
47:and chemical
46:
42:
41:precipitation
38:
34:
30:
26:
22:
827:
820:
735:
730:
703:
699:
689:
679:
677:
653:
631:
583:hemimorphite
577:
555:
515:Chalcopyrite
513:
501:
498:Primary zone
492:
474:enrichment.
463:
443:
366:pyromorphite
354:precipitates
311:
284:
260:
196:
193:Leached zone
178:
161:
152:
106:
60:
28:
18:
641:melanterite
607:smithsonite
539:brochantite
446:water table
440:Water table
430:smithsonite
346:polymorphic
198:Groundwater
722:References
668:phosphates
660:phosphorus
579:Sphalerite
480:chalcocite
340:(also CaCO
303:carbonates
158:Gossan cap
70:chalcocite
61:enrichment
49:weathering
700:supergene
680:supergene
678:The word
674:Etymology
664:arsenates
619:willemite
617:-bearing
615:manganese
569:cerussite
561:anglesite
535:covellite
476:Covellite
450:oxidizing
386:malachite
358:anglesite
338:aragonite
287:oxidizing
218:solutions
177:(FeO(OH)·
94:djurleite
78:covellite
45:oxidation
29:supergene
859:Category
716:Hypogene
710:See also
704:hypogene
537:CuS and
454:reducing
428:O); and
328:(CaMg(CO
326:dolomite
307:limonite
299:sulfates
291:reducing
245:O + 15 O
175:limonite
171:goethite
82:digenite
33:hypogene
23:deposit
656:arsenic
523:bornite
486:S) and
478:(CuS),
472:sulfide
444:At the
422:cuprite
420:), and
402:azurite
318:calcite
92:), and
80:(CuS),
53:oxidize
25:geology
742:
695:-γενής
633:Pyrite
557:Galena
465:Copper
382:copper
364:) and
305:, and
241:+ 12 H
202:oxygen
187:gossan
163:Pyrite
66:copper
690:-gene
685:super
517:CuFeS
456:one.
432:(ZnCO
380:Cl);
360:(PbSO
356:like
336:) or
320:(CaCO
237:4 FeS
119:Zones
740:ISBN
702:and
666:and
658:and
643:FeSO
613:and
609:ZnCO
597:(OH)
571:PbCO
567:and
563:PbSO
549:(OH)
468:ions
416:(OH)
396:(OH)
351:lead
301:and
216:and
204:and
165:(FeS
76:S),
651:O.
647:.7H
635:FeS
625:SiO
605:O,
529:FeS
482:(Cu
436:).
424:(Cu
408:(CO
404:(Cu
400:),
392:(CO
388:(Cu
372:(PO
368:(Pb
324:),
269:(SO
265:(Fe
115:).
113:atm
111:(1
96:(Cu
84:(Cu
72:(Cu
21:ore
19:In
861::
837:^
796:^
784:^
766:^
750:^
629:.
621:Zn
601:.H
589:Si
585:Zn
575:.
553:.
545:SO
541:Cu
533:,
525:Cu
506:.
344:,
253:SO
228:SO
102:16
98:31
90:10
86:18
27:,
692:(
649:2
645:4
637:2
627:4
623:2
611:3
603:2
599:2
595:7
593:O
591:2
587:4
573:3
565:4
551:6
547:4
543:4
531:4
527:5
519:2
484:2
434:3
426:2
418:2
414:2
412:)
410:3
406:3
398:2
394:3
390:2
378:3
376:)
374:4
370:5
362:4
342:3
334:2
332:)
330:3
322:3
275:3
273:)
271:4
267:2
255:4
251:2
247:2
243:2
239:2
230:4
226:2
222:2
183:2
181:H
179:n
167:2
100:S
88:S
74:2
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