Every thing about the Kyburr Crystal

I know that Leia and Luke found a crystal on Memban. But before Vater can capture it, they defeat him by cutting his arm.
Later I saw a midichlorian list of the main SW characters and I saw Darht Sidious/ the Emperor with and without Kyburr Crystal. With, he had more midichlorians then without.
Maybe somebody know something about it, something I did not know?