Can you take some more pictures? Close-ups would be helpful...
Based purely on appearance this looks like a group of quartz crystals with some iron stains from hematite. Other possibilities are calcite and danburite. Quartz is hardness 7, calcite is hardness 3 so if a knife blade can scratch it then it's probably calcite. If it doesn't react to dilute acid then that eliminates calcite.
Yes, mostly likely quartz with iron stains, like stonesinger suggested. But an additional possibility could be danburite. Its hard to tell based on the crystal structure but if you can get a better close-up of the crystal that can be determined.
I agree with the first response. This looks like clear quartz with iron stains. Id probably disagree with danburite though, its not the right shape for danburite.
It looks like quartz.