Lava flow in the western part of Hawai’i that originated from the Hualalai volcano and formed in 1800…1801 is remarkably rich in xenoliths. It is an aa lava. Many nice examples of dunite and peridotite (rocks from the mantle) can be found with a little bit of patience and searching.
This is how they look. It often pays to turn the other sides of the clinkery chunks of aa lava because some nice xenoliths are not immediately visible.
I spent maybe 20 minutes looking for the xenoliths and found a nice collection of rocks containing xenoliths of peridotite and dunite for a picture. I scattered most of the pieces after taking the picture for you to find them again.
Only a very small part of this dunite xenolith was initially visible. After spliting the rock with a hammer, this beautiful example of the mantle embedded in vesicular basaltic lava was revealed. The sample is 8 cm in width.
There is a possibility that these xenoliths are not xenoliths in the strict sense of the word. They might be genetically related to the lava which embeds them. If this is the case, they should be called inclusions instead of xenoliths.
The lava flow is quite wide and long. There is little chance that the location I visited is the best place to find xenoliths there. But here are the coordinates if you are interested to follow my footsteps: 19° 46′ 40″ N 155° 54′ 53″ W. Altitude 620 meters.