

Septarian concretion


Copper vein inside malachite
At least the rocks are getting bigger...LOL...these are hand sized or larger.
The upper rock is a Sepatarian concretion. The word Concretion is from Latin, and means "grow together". Concretions are collections of minerals that come together when water carries them into seeps in some sedimentary rocks or soils. The minerals eventually harden into crystal habits.
The second rock is an absolutely wonderful specimen from the Keweenaw area of Upper Michigan. It contains very clear veins of pure copper within a rock body (malachite?) There is evidence that Native Americans mined copper in the Upper Peninsula of Michigan as early as 7,000 years ago. They would put rocks like this in a fire and then after they were heated up, pour cold water on them to crack the rock and extract the copper!
Super!