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# Correction to: The inherent link between ore formation and geometallurgy as documented by complex tin mineralization at the Hämmerlein deposit (Erzgebirge, Germany)

Erratum to: Mineralium Deposita

We noticed that the presented formula for calculation of the MAMA ratio requires clarification in two places.

(1) The formula for the MAMA ratio as it appears in the original version of the manuscript

$${\mathrm{MAMA}}_{target}=\alpha\ \frac{\mathbf{M}\mathrm{ineral}\ \mathbf{A}\mathrm{ssociation}\ \left({\mathit{\operatorname{Min}}}_X\right)\ \mathrm{with}\ \mathrm{target}\ \mathrm{mineral}\ }{\mathbf{M}\mathrm{ineral}\ \mathbf{A}\mathrm{rea}\ \left({\mathit{\operatorname{Min}}}_X\right)\ }$$

suggests to the reader to use absolute values for Mineral Area (MinX). Instead, relative values were used to calculate the MAMA ratio. We would like to correct the formula to

$${\mathrm{MAMA}}_{target}=\alpha\ \frac{\mathbf{M}\mathrm{ineral}\ \mathbf{A}\mathrm{ssociation}\ \left({\mathit{\operatorname{Min}}}_X\right)\ \mathrm{with}\ \mathrm{target}\ \mathrm{mineral}\ }{\mathbf{M}\mathrm{ineral}\ \mathbf{A}\mathrm{rea}\ \left(\%\right)\ \left({\mathit{\operatorname{Min}}}_X\right)\ }$$

(2) Normalization of MAMAtarget values with α may be a justifiable step when comparing between datasets from different sampling locations. However, we generally recommend choosing a value of α = 1 when there are no clear indications that such normalization is necessary.

An example—where cassiterite is the target mineral and chlorite is MinX—may further help to clarify the MAMA formula: The length of the grain boundaries between chlorite and cassiterite in a given slab measured is X mm. The total length of the grain boundaries of chlorite with all minerals is Y mm. The mineral association value is then X/Y. This value is normalized to the area fraction of chlorite in the sample, which gives the dimensionless MAMA ratio.

We would like to thank Dr. Max Frenzel from Helmholtz-Zentrum Dresden-Rossendorf, who informed us about the discrepancies.

## Author information

Correspondence to Marius Kern.