Silver Bell
Pima County, Silver Bell district (Arizona), United States
PorphyriesCu (Mo)
- Type
- Porphyry copper with supergene enrichment
Four to five small aligned Laramide porphyry intrusions (below 5 km²), protore at 0.15 to 0.28 % Cu, minor skarn. Laramide porphyry copper with minor potassic and extensive quartz-sericite alteration, controlled by stockwork fracturing; supergene enrichment active since about 10 Ma, oxidation still under way at surface. Mathur et al. (2010): the most 65Cu-depleted leach cap and the most enriched enrichment zone of the three deposits, a sign of deeper leaching. Table 3: chalcocite 4.9 ‰ (printed "49"), hematite and goethite -8.4 ‰, chalcopyrite -2.6 ‰ (after Mathur et al., 2009). Indicative coordinates: general position of the mine, not published by Mathur et al. (2010), to within 5 km.
δ65Cu in ‰ (per mil) Values of the same system
Standard : NIST SRM 976
| Value | Range | n | Mineral or matrix | Source |
|---|---|---|---|---|
| −5.7 ± 7.2 ‰ | −13.5 / 6.8 ‰ | 11 | leach-cap minerals (iron oxides and sulfates) Mean and standard deviation recalculated from 11 analyses, -13.5 to +6.8 (hole 120, 3 ft (hm-goe) -10.4; hole 120, 20 ft (hm-goe) -6.7; hole 120, 40 ft (hm) -10.4; hole 120, 75 ft (hm-goe-qtz) -10.2; hole 120, 94 ft (qtz-hm) -8.6; hole 120, 155 ft (hm-goe-qtz) -3.5; hole 120, 158 ft (jr-qtz-goe) -0.4; hole 476, 59 ft (goe-jr) +6.4; hole 476, 85 ft (goe) +6.8; hole 525, 2 ft (qtz-goe) -12.3; hole 525, 24 ft (qtz-goe) -13.5). Drill hole and depth in feet, XRD-identified minerals in brackets. Rock Cu grade (%): hole 120, 3 ft 0.00; hole 120, 20 ft 0.14; hole 120, 75 ft 0.40; hole 120, 94 ft 0.79; hole 120, 155 ft 0.96; hole 120, 158 ft 0.96; hole 476, 59 ft 1.40; hole 476, 85 ft 1.46; hole 525, 2 ft 0.03; hole 525, 24 ft 0.08. XRD abbreviations: an antlerite, bor bornite, cc chalcocite, chr chrysocolla, cpy chalcopyrite, cu native copper, cup cuprite, cv covellite, goe goethite, hm (or hem) hematite, jr jarosite, mal malachite, mgn magnetite, py pyrite, qtz quartz, tc tenorite; amorphous: amorphous phase. | Mathur et al. (2010), Patterns in the copper isotope composition of minerals in porphyry … |
| 4.3 ± 6.2 ‰ | −8.3 / 8.1 ‰ | 6 | leach cap to enrichment transition minerals Mean and standard deviation recalculated from 6 analyses, -8.3 to +8.1 (hole 120, 194 ft (py-hem) -8.3; hole 476, 10 ft (cc-mgn) +6.3; hole 476, 31 ft (amorphous) +6.2; hole 476, 32 ft (cc-mal) +5.8; hole 476, 40 ft (amorphous) +7.6; hole 476, 44 ft (cup) +8.1). Drill hole and depth in feet, XRD-identified minerals in brackets. Rock Cu grade (%): hole 120, 194 ft 0.18; hole 476, 10 ft 1.04; hole 476, 31 ft 1.81; hole 476, 32 ft 1.81; hole 476, 40 ft 2.08; hole 476, 44 ft 2.08. XRD abbreviations: an antlerite, bor bornite, cc chalcocite, chr chrysocolla, cpy chalcopyrite, cu native copper, cup cuprite, cv covellite, goe goethite, hm (or hem) hematite, jr jarosite, mal malachite, mgn magnetite, py pyrite, qtz quartz, tc tenorite; amorphous: amorphous phase. | Mathur et al. (2010), Patterns in the copper isotope composition of minerals in porphyry … |
| 3.8 ± 5.8 ‰ | −7.8 / 8.3 ‰ | 9 | supergene enrichment zone minerals Mean and standard deviation recalculated from 9 analyses, -7.8 to +8.3 (hole 476, 54 ft (cup) +7.3; hole 476, 88 ft (cc) +6.3; hole 476, 102 ft (goe-jr-qtz-cup) +6.6; hole 476, 106 ft (cup) +6.7; hole 525, 90 ft (mal) -7.8; hole 525, 118 ft (cc-py-goe) -4.7; hole 525, 140 ft (qtz-jr) +4.3; hole 525, 180 ft (qtz-py-cpy) +7.2; hole 525, 185 ft (py-hm-goe-qtz) +8.3). Drill hole and depth in feet, XRD-identified minerals in brackets. Rock Cu grade (%): hole 476, 54 ft 1.88; hole 476, 88 ft 4.69; hole 476, 102 ft 1.71; hole 476, 106 ft 1.71; hole 525, 90 ft 0.95; hole 525, 118 ft 0.49; hole 525, 140 ft 1.17; hole 525, 180 ft 1.76; hole 525, 185 ft 1.76. XRD abbreviations: an antlerite, bor bornite, cc chalcocite, chr chrysocolla, cpy chalcopyrite, cu native copper, cup cuprite, cv covellite, goe goethite, hm (or hem) hematite, jr jarosite, mal malachite, mgn magnetite, py pyrite, qtz quartz, tc tenorite; amorphous: amorphous phase. | Mathur et al. (2010), Patterns in the copper isotope composition of minerals in porphyry … |
Deposits of the same type
- Ray United States
- Morenci United States
- Bingham Canyon United States
- Bingham Canyon United States
- Climax United States
- Henderson United States
- Battle Mountain district (Copper Basin, Elder Creek) United States
- Granisle Canada
Cite this page
IsoFind Atlas (2026). Silver Bell, isotope signatures. https://www.isofind.tech/isotopes/en/deposits/silver-bell/ (accessed 2026-10-22).
@misc{isofind2026silverbellisotopesignatures,
title = {Silver Bell, isotope signatures},
author = {{IsoFind Atlas}},
year = {2026},
url = {https://www.isofind.tech/isotopes/en/deposits/silver-bell/},
note = {Accessed 2026-10-22}
}Updated : 2026-10-22