As the others have said looks like quartz, scratch test it to be sure. What I notice thats a bit different on it is that it looks as though its been attatched to a larger aggregate at some point in time probably at the bottom of a shallow sandy creek. Your first pic shows a definate pyramid crystal form but it has been softened and smoothed to a melted glassy finish in some places by the movement of water and sediment. while the second shows the base of the crystal where it has seperated from its join with another crystal or base mineral.
Quartz is always good to find even if its just nice species to look at or trade.
Happy hunting, GW
but still a nice looking rock.
