One of the essential conditions for the validity of a transaction in the Iranian legal system is that its subject-mater must be certain and definite. In other words, the object of a transaction should not be ambigious and uncertain. However in Contracts on transfer of mines, specially subterrenean mines, respect of the condition is very hard. It appears that in such cases expression of parties to the subject-matter and its specifications is efficient for conclusion of the contract. Breach of the obligations would have different effects which have been discussed in this article.
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