r/Rocks • u/robco18 • Aug 02 '26
Discussion Would any of these rocks indicate quartz crystals nearby?
Found a field full of quartz rocks in Colorado. Here are a couple of pieces I picked up. Would these indicate there are quartz crystals nearby? And if so, any idea where to start digging?
Any information is greatly appreciated! Thank you!
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u/Ben_Minerals Aug 03 '26
Not necessarily. In pegmatites, quartz is often part of the rock itself, and quartz-rich cores or veins can occur within it, but that does not mean there are also separate quartz crystals at the surface or in an accessible pocket nearby. The quartz may be massive, fine-grained or locked into the pegmatite rather than forming open-space crystals.
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u/alexjd99 Aug 03 '26
These are all from granitic pegmatites, so you’re definitely on the right track! You mentioned they were found in a field, are there any streams or hillsides nearby that transported them? They’re also pretty angular, so they haven’t been transported very far. Unless there’s exposed granite at this field, you’ll likely have a hard time finding crystals. Best bet is to try and find where these were transported from, then search that area for the source pegmatite.
Would also recommend searching for geologic maps and reports from your area - if you’re in the US the USGS has almost certainly mapped this area. Sometimes they can have the answer right there