Logged to 1398.5 feet, learning more about fracture fill

We logged 95.1 ft of boxed rock core today, ending the day at a depth of 1398.5 ft.  Most of the day was spent logging, with a brief break to move boxes between the different buildings and areas we use.  We're starting to get to depths with a lot of "fracture fill," which interestingly remains a bit wet even after days in the drying area.  My current theory about this material is that it is water-absorbing clay produced by chemical interaction of the rock and volcanic glass with groundwater.  We hope to study this fracture fill material over the summer and figure out the details of its composition.  Here is a picture of what it looks like in a pahoehoe flow, filling multiple fractures in and around the vesicular lava: