Firstly: Defining Ores
Ma`din linguistically: originates from the root verb `adana. One `adana in some place if one resides therein. From this, the word ma`din is where people permanently reside. They stay there during the summer and winter, or due to Allah establishing their provision there
The origin of ma`din: is a place where settlement occcurs, then becomes used for the things that settle in said place.
Ma`din technically: is anything that is extracted from the earth that is created within it. It is other than the nature of the earth, valuable, and holds properties that make it useful, like gold, silver, sapphire, emerald, bitumen, petroleum, and their like.
Secondly: Types of Ore
Ores are of three types in terms of their essence:
The first type: is that which is solid but melts and becomes malleable under heat treatment; like gold and silver, iron, lead, brass, etc. This type can also be subjected to hammering and pulling, and is therefore used for the manufacturing of tins and wires and their like.
The second type: is that which is solid that but does not soften under heat treatment, like gypsum, zinc bloom, and arsenic.
The third: is what is not solid, like water, bitumen, petroleum, and mercury.
Ores are of two types in terms of their extraction process:
The first type: is an apparent ore, and it is that which is extracted without treatment, and the treatment is in purifying it, like acquiring gasoline from petroleum or sulphur from brimstone.
The second type: is a submerged ore, and it is that which cannot be extracted except through treatment, like gold, silver, iron, and copper.
Thirdly: The Ruling of Charity on Ores
Charity on ores is wajib generally. Consensus has been quoted on this by: al-Nawawi, al-Qarafi, and al-`Iraqi.
Fourthly: The Nature of Ore Upon Which Charity is Wajib
Scholars have differed over the nature of ores upon which charity is wajib according to many views, the strongest of which are two:
The first: is that it is a condition that the ore be of gold or silver. This is the position of the Malikis, Shafi`is, a position among Hanbalis, chosen by Ibn Hazm and al-Albani, and al-San`ani held it as the apparent view.
The second: is that it is not a condition that the ore be of gold or silver, rather, anything of value that is found in the earth is included. This encompasses gems, gold and silver, lead and copper, iron, as well as liquid ores, like bitumen, petroleum, and their like.  Al-`Iraqi said: “Ibn Hazm mentioned that the whole Ummah is in consensus that there is no charity payable on brass, iron, lead, and tin, and that a group have stated it as wajib if it is mixed with gold or silver. There is no charity over it if it is pure. End quote. The Hanafis and the Hanbalis deem it wajib that charity be paid on all ores, even if they are not gold or silver, except that the Hanafis hold the position that a fifth is wajib and they considered it a tax, while the Hanbalis hold the position that a quarter of a tenth is wajib and they considered it legal charity.” Tarh al-Tathrib (25/4) This is the position of the Hanbalis, the old position of al-Shafi`i, and it is the choice of al-Qaradawi, and Ibn `Uthaymin precautionarily.
Fifthly: The Wajib Amount Given in Charity on Ores
The wajib amount for charity on ores is a quarter of a tenth. This is the position of the majority: Malikis,  Malikis conditioned this for what is extracted from ores through a costly process, as for a little (nudrah – lit. rarity) of it without said process, then this is buried wealth, and its ruling takes its ruling: a fifth. It is narrated from Malik that the ruling of a little ore found is the same as buried wealth that is costly to extract. Shafi`is, Hanbalis, and the majority of scholars.
Sixthly: The Nisab of Charity on Ores
It is a condition for charity on ores to become wajib that they reach the nisab. This is the position of the majority: Malikis, Shafi`is, Hanbalis, and Dawud al-Zahiri.
Seventhly: The Passing of a Calendar Year
Charity on ores is wajib when discovered, and it is not a condition that a calendar year pass. This is by agreement of the four schools of jurisprudence, and the vast majority of scholars.
Eighthly: Where Charity in Ores is Spent
Charity on ores is spent on where legal charity is spent (the eight valid avenues). This is the position of the majority: Malikis, the correct position among Shafi`is, and the position of the Hanbalis.