Houcao
Central Guizhou, Bozhou district (Zunyi), China
OtherAl (Ga)
- Type
- Ga-rich karst bauxite
Bauxite of a palaeo-karst depression (orebody about 70 m thick) in the Jiujialu Formation (Lower Carboniferous), on Ordovician shales and dolomites of the Meitan and Tongzi formations or Cambrian dolomites of the Loushanguan Group, below carbonaceous shales of the Liangshan Formation (Lower Permian). Clayey marginal profile H1 with Ga/Al matching the source rocks; base of the central profile H2 rich in euhedral pyrite intergrown with illite, with Ga/Al of 4.35 to 5.54 × 10⁻⁴: Ga-Al decoupling ascribed to an acidic environment (pH below about 5.5) that leaches aluminium more than gallium (Zhang et al., 2026). Indicative coordinates, read from the location map (south of Zunyi).
δ71Ga in ‰ (per mil) Values of the same system
Standard : NIST SRM 994
| Value | Range | n | Mineral or matrix | Source |
|---|---|---|---|---|
| 1.25 ± 0.03 ‰ | 1.21 / 1.31 ‰ | 8 | pyrite-free bauxitic clay (marginal profile H1, HC1-3 to HC1-10) Mean and standard deviation recalculated from 8 analyses, 21 to 30 µg/g Ga, Ga/Al of 2.53 to 2.66 × 10⁻⁴ as in the source rocks (Ga and Al coupled). Values from Table S1; bauxite lighter than its source rocks (shales and carbonates), δ71Ga anticorrelated with Ga content: weathering residue that lost heavy gallium. | Zhang et al. (2026), Decoupling of gallium and aluminum in bauxite deposits: Constraints … |
| 1.24 ± 0.06 ‰ | 1.16 / 1.34 ‰ | 7 | pyrite-free bauxite (upper part of the central profile H2, HC2-6 to HC2-12) Mean and standard deviation recalculated from 7 analyses, 50 to 92 µg/g Ga, Ga/Al of 2.30 to 2.93 × 10⁻⁴ (Ga and Al coupled). Values from Table S1; bauxite lighter than its source rocks (shales and carbonates), δ71Ga anticorrelated with Ga content: weathering residue that lost heavy gallium. | Zhang et al. (2026), Decoupling of gallium and aluminum in bauxite deposits: Constraints … |
| 1.2 ± 0.04 ‰ | 1.13 / 1.27 ‰ | 7 | pyrite-bearing bauxite (lower part of the central profile H2, HC2-1-1 to HC2-5) Mean and standard deviation recalculated from 7 analyses, 83 to 121 µg/g Ga, Ga/Al of 3.35 to 5.54 × 10⁻⁴ increasing downwards; the five lowest samples (Ga/Al above 4.35 × 10⁻⁴) are decoupled, the most Ga-rich (HC2-1-1) being the lightest (1.13 ‰). Values from Table S1; bauxite lighter than its source rocks (shales and carbonates), δ71Ga anticorrelated with Ga content: weathering residue that lost heavy gallium. | Zhang et al. (2026), Decoupling of gallium and aluminum in bauxite deposits: Constraints … |
Deposits of the same type
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- Anning (carbonate-hosted clay-type lithium) China
- Deep lithium-bearing brines of the Jiangling Basin China
- Huainan-Huaibei coalfield China
- Lithium-rich salt lakes of the Qaidam Basin (Dongtai, Xitai, Yiliping, Qarhan) China
- Dezong Mahai (Balun Mahai basin clay-type lithium) China
- Kinta Valley Malaisie
Cite this page
IsoFind Atlas (2026). Houcao, isotope signatures. https://www.isofind.tech/isotopes/en/deposits/houcao/ (accessed 2026-10-15).
@misc{isofind2026houcaoisotopesignatures,
title = {Houcao, isotope signatures},
author = {{IsoFind Atlas}},
year = {2026},
url = {https://www.isofind.tech/isotopes/en/deposits/houcao/},
note = {Accessed 2026-10-15}
}Updated : 2026-10-15