Volcanic Rock on the grand Mesa

I traveled with a church group to the Grand Mesa in Colorado.
Its a high plateau-like area with a bunch of lakes all at or above 10,000 feet. One of my favorite spots.

While hiking Craig's Crest we saw some black rock laying around which i previously heard people identify as volcanic. But what interested me to learn in the Lab 2 were some of the features and implications of those features for this rock. The texture was very vesicular. It had the sponge-like appearance which means the rock cooled quickly which preserved the bubbles that were bursting as the air escaped. So this rock my son and i were looking at is pyroclastic (meaning it formed from cooling molten lava mid-air after an eruption which is pretty bad ass) and a "Cinder" because of its size.

I have another volcanic rock at home but it is not very vesicular which i take to mean it cooled slower than the ones on the Grand Mesa. It was pretty neat to find out such specific information about it in the lab 2 after we got home.