What is the minimum threshold (Nisab) for Zakah on extracted minerals?

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The Nisab for minerals is twenty Mithqals of gold, or two hundred Dirhams of silver, or the equivalent value thereof in other substances. This is the established position of Al-Shafi'i. The obligation is established based on the general saying of the Prophet, peace be upon him: "There is no Zakah on less than five Uqiyyah (ounces)." Another evidence is: "There is nothing due on ninety and nine Dirhams." Furthermore, the Prophet, peace be upon him, stated: "There is nothing due on gold until it reaches twenty Mithqals." Zakah is obligatory here out of a duty of solidarity (Muwāsāh) and gratitude for the blessing of wealth, thus a Nisab is considered, similar to other forms of Zakah.