fuchsite

The green color of the rock is the result of chromium in the mica which is also known as fuchsite.

Chrome-bearing fuchsite (a variety of muscovite mica) is the classic inclusion, and gives a silvery green or blue sheen.

The green, chromium-rich variety is called fuchsite; mariposite is also a chromium-rich type of muscovite.

In aventurine quartz, chrome-bearing fuchsite makes for a green stone and various iron oxides make for a red stone.

Aventurine is often banded and an overabundance of fuchsite may render it opaque, in which case it may be mistaken for malachite at first glance.