The following is the translation of an Arabic Q&A from the website of the noble jurist, Islamic politician and mufassir Sheikh `Ata’ Ibn Khalil Abu Rashta (Allah preserve him).
With respect to the subject of al-Rikaz, it is mentioned in the book, al-Amwal (The Funds) that there is one fifth of al-Rikaz, and the question is: with respect to the forms and metals that have a specific significance or express a specific view about life such as: crosses, and statues that are manufactured from ivory, is it permissible to possess them if they were from al-Rikaz? Which means: selling them, benefitting from their costs, and then extracting a percentage of fifth from them?
According to al-Rikaz, if the material is prohibited, then it is prohibited to own, buy, or sell it.
Thus, if a Muslim finds a buried Rikaz that is made up from prohibited material "crosses, statues", it is prohibited for him to possess it due to its prohibited form. Hence, it is permissible to break it so as to change its prohibited form, and sell its broken parts, and the fifth of the cost should be paid to the Khilafah if it existed since it is paid to the state to spend on the interests of Muslims and needy. And if the Khilafah was non-existent, the fifth of the cost should be paid to the poor, needy, and the interests of Muslims, and the remaining 4/5 percentage is for him.
This is as long as the statue and the cross are not from the bones of dead because breaking it won't remove the characteristic of the dead from it.
However, if it was from the bones of dead bodies or their horns, there is a difference in opinion between jurists regarding its purity (tahara) or filthiness (najasah)... The opinion that I outweigh (muraj'ih) is that which says that it is filthy and the characteristic of the dead bodies is applied on it.
Allah سبحانه وتعالى said:
قَالَ مَنْ يُحْيِي الْعِظَامَ وَهِيَ رَمِيمٌ
"He says, 'Who will give life to bones when they are decayed?'"
The textual meaning of "yuhyi" (give life) with the bones shows that the bones of the dead bodies are considered dead also.
In conclusion, if the statue or the cross is from any part of a dead body, it is not permissible to benefit from it even if it is broken because the parts of a dead body is considered also dead, and its ruling is applied on it.
18 Thul Qi'da 1433 AH