The exposed bedrock on the top of Compass Hill was very friable. This sample dislodged under me!
The BGS viewer tells me it is Hawaiite but that it is aphyritic. I had to look that up. It means that it doesn't have phenocrysts - crystals that are obviously much larger than the other grains. I can see some much larger bits in this rock. It probably means that they don't count as phenocrysts. See here for Hawaiite from Rum. Here for details of what Hawaiite is.
