Scientists say the fragments are magmatic rocks. Magmatism is the main process by which water moves from the core of planets to their surface. From a magma chamber below Mars "It is a remarkable experience to hold it in your hand," Bruno Fectay said. "When you hold it you are in a Martian magmatic chamber, deep in a volcano under the surface of Mars. "We will never be able to go to such a place. This rock is our passport." Further analysis will help clarify the processes that produced magmas on Mars, and perhaps make it possible to estimate the quantity of fluids - and therefore water - released by volcanic activity on the planet in the past.
http://news.bbc.co.uk/2/hi/science/nature/3414143.stm
