Lanmuchang Tl deposit, Huijiabao gold field, Xingren County, Qianxinan, Guizhou, Chinai

Regional Level Types
Lanmuchang Tl deposit	Deposit
Huijiabao gold field	- not defined -
Xingren County	County
Qianxinan	Prefecture
Guizhou	Province
China	Country

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PhotosMapsSearchMineralogy

The thallium-rich orebodies extend over an area of about 1.5 square km. They contain lorándite as the major ore mineral. Major geogenic pollution affecting human health has been documented.

The deposit was formed by biomethallogenesis (involving the enrichment of Tl in micro-paleo-animals in rocks and ores, biofossil casts in Tl-rich ores, the involvement of bio-sulfur in minerogenesis, and the enrichment of biogenetic organic carbon in Tl ores) and subsequent hydrothermal reworking (Zhang et al., 2007).

The deposit was originally formed in the Late Permian. Subsequently, hydrothermal reworking took place during the Middle Triassic (Zhang & Zhang, 2000).

The Lanmuchang Anticline extends northeastward (40–60°) and is ~700 m long and ~250 m wide. Fault structures primarily developed in two groups: northeast- and approximately north-south-trending structures. The north-south-trending Huilong Fault cuts through the Lanmuchang Anticline at a breaking distance of ~200 m. Exposed strata primarily include the Lower Permian Maokou Formation; Upper Permian Longtan, Changxing, and Dalong Formations; and Lower Triassic Yelang Formation. Ore-bearing rocks are diverse and primarily include limestone, silty claystone, carbonaceous siltstone, and shale, which are typically mixed to form banded and laminated structures. Due to the diversity of the ore-bearing strata, more than 20 mineralized horizons have been identified. Hydrothermal alteration is dominated by low-temperature alteration, including sulfidation, silicification, decarbonation, carbonation, and kaolinitization. Kaolinitization is responsible for the formation of not only kaolinite but also subordinate amounts of illite.
According to the characteristics of ore paragenesis, texture, and alteration, the mineralization can be preliminarily divided into three stages: pyrite–quartz–illite (I), cinnabar–kaolinite–calcite–fluorite (II), and lorándite–pyrite–quartz (III). Stage I is the primary mineralization stage of Au and the initial enrichment stage of Hg and Tl, and these mineralizing elements are primarily enriched in pyrite. Stage II is the primary Hg mineralization stage, characterized by cinnabar enrichment. Stage III is the primary Tl mineralization stage, characterized by lorándite enrichment.

The mineralized layers of the Lanmuchang Hg-(Tl) deposit extend up to 15 layers, primarily distributed in the Permian Longtan Formation and Changxing Formation, followed by the Triassic Yelang Formation. These orebodies owe their formation and occurrence to a combination of structural and stratigraphic controls, characterized by distinctive layered and lens-shaped features that closely resemble the surrounding sediments. The mercury content in the orebodies typically ranges from 0.08% to 0.3%, with the highest concentration reaching 1.17% and the resource amounting to 4874 tons. Thallium grades generally fall between 0.01% and 0.02%, peaking at 0.035%, with resources exceeding 500 tons.

Commodity List

This is a list of exploitable or exploited mineral commodities recorded at this locality.

Mineral List

40 valid minerals. 1 (TL) - type locality of valid minerals.

Rock Types Recorded