Continuing my series where I try to define words of volcanic interest, the new Eruptions Word of the Day is a favorite of mine, mostly because my undergraduate thesis on Vinalhaven Island in Maine ended up dealing with a lot of these types of deposits ... so, without further ado, the word is peperite!
Now, what exactly is a "peperite"?
Well, a picture is worth 1,000 words, right (so that will save me some time):
Peperite in the Vinalhaven Diabase, Vinalhaven Island, Maine. Image by Erik Klemetti. Click on the image to see a larger version.
Let's make some observations:
The rock is full of red-to-black clasts of various sizes and shapes.
The clasts are almost all basaltic andesite in composition.
Some of the clasts look like they have a "chilled" margin, where hot molten material came into contact with colder material.
Some of the clasts look like you could ...
