The black talc in Guangfeng is a Sinian sedimental-metamorphic transformation type deposit, and its mineralization process is divided into3One stage:

1. Sedimentary diagenetic stage

About a year ago8During the Sinian period of hundreds of millions of years, in the shallow Marine environment, a large amount of magnesium-rich silicate clay, siliceous substances, carbonates, and algal organic matter were deposited, forming magnesium-rich mudstone layers. The mixture of organic matter made the ores black.

2. Diagenetic compaction stage

After long-term deep burial and compaction, the magnesia clay undergoes initial dehydration and recrystallization, forming talc precursor minerals.

3. Regional deterioration transformation

Under the influence of tectonic movement and hydrothermal action, magnesia mudstone undergoes metamorphic reactions, with magnesium and silicon reconstituting, and organic matter being retained and encapsulated, eventually forming black talc ore bodies.

• Occurrence strata: Doushantuo Formation of the Zhendan System/In the Chaoyang Formation, the ore bodies are distributed in a northeast-oriented, layered or quasi-layered pattern, with stable strata and thick ore layers.

• Core feature: Unlike ordinary hydrothermal talc, the organic matter is evenly distributed among the talc crystals, which is the fundamental reason for the black color of Guangfeng black talc.