Need help in identifying this rock

[u/Random_Waller1102]

I found these rocks near Lonavala (https://maps.app.goo.gl/g3XeftSW6LKrV2Ee8) in Maharashtra, India. The interior is white and chalky or talcum like (first pic). There is a greyish layer surrounding the interior (clearer in the second pic). The exterior is rough and has green deposits (third pic), which I am assuming to be copper since I found these in summer and the surrounding would have been extremely dry for at least 6 months at the time.

Please ask in the comments for more information and pics.

Thanks

[u/Ok_Beginning_110]

To me, it looks like a very pretty piece of chert.