The Stones for the Pillars

Question :

Where are the stones for the pillars taken from and what is the description of the stone? Also, what is the ruling on washing the stone?

Answer:

The stones are taken from Mina and if they are taken from Muzdalifah on the day of the Eid, there is no harm in that. It should be seven stones on the day of the 'Eid, and it is not legislated to wash them. Rather, they should be taken from Mina or Muzdalifah and the person throws them. They also may be taken from any other place of the Haram (the Sacred Area of Makkah) and that is sufficient and there is no harm in it. During the days of At-Tashreeq the person picks them up from Mina, collecting 21 stones each day. If the person is in a hurry to leave, he takes 42 stones for the 11th and 12th day; and if he is not in a hurry to leave, he takes 63 stones. These stones should be pebbles for throwing, and they resemble the droppings of the medium sized sheep. They are larger than the chickpea and smaller than the hazelnut, as the Fiqh scholars have said. They are called throwing pebbles, as was mentioned previously, and they are slightly smaller than the droppings of sheep.

Source:
Ash-Shaykh Ibn Baz
Fatawa Islamiyah, Vol. 4 Pages 237-238