Primary ore → placer ore, such as tin, tungsten, gold and diamond (Figure 5- 14).
Primary ore → oxidized ore (weathering crust ore), such as primary ore of iron, copper and manganese → iron cap.
Graphite ore → anthracite.
Metallogenic system theory
Can be converted into other types of minerals (deposits) need to have certain conditions, from the known examples, there are the following situations:
Fig. 5- 14 metallogenic model of sand-tin deposit in Shanzhai basin, Yunnan province (according to Chen Huahui et al. 199 1)
1) minerals (elements or compounds) are homogeneous and heterogeneous, for example, carbon can be transformed into coal, graphite, diamond and so on. And there is a material basis for transforming into various types of minerals.
2) Some valence-changing elements, such as iron, uranium and manganese. Due to different redox conditions, various mineral types and mineral assemblage types can be formed, so there is the possibility of deposit type transformation.
3) Some chemical elements have the properties that can be produced under various physical and chemical conditions, that is, the so-called "broad spectrum", "universality" and "various affinities", so they can form various deposit types, such as copper, iron and gold deposits. Some minerals lack "multiple kinship", such as chromite, which has only several genetic types of deposits, namely primary magma type and secondary eluvial or alluvial placer type.
Whether a certain type of deposit is transformed from another type of deposit or gradually enriched by dispersed substances needs careful study. If the conditions are met, it is possible to find out its ins and outs. See figure 5- 15 below.
Figure 5- 15 deposit type conversion under different conditions
When the original deposit type is still partially preserved and the occurrence position is adjacent to the newly derived deposit type, it is possible to find out the genetic relationship between them.
In particular, there is a special situation in the change of deposit types, that is, when the original deposit is superimposed (superimposed mineralization) by another type of deposit, the original single deposit type is transformed into multiple types of polygenic deposits. This situation is not uncommon. See Chapter 10 "Superimposed Metallogenic System and Polygenetic Deposits" for details.