Stone tool lesson #43B

It is always worth looking around corporate planters and parking lots when the landscaping uses large, water-polished stone pebbles for ground cover. There may be stone tools mixed in with the unmodified rocks. Here for example is an unmodified rock on the left and a modified one on the right - from the parking lot of Dassaulte Systems Waltham, MA.(These are about 2.5-3 inches long.)

All the surfaces of the pebble on the right are smooth, except the one facing camera. The visible rough surface , although worn away and partially reverted to being smooth, shows the concave faceting and alternate flaking characteristic of a stone tool.

It is interesting to speculate about the age of this item and about how it went back into the water a second time. Unfortunately, I don't know where the pebbles came from and I doubt it is local. See also here.