What treasure this cache in this rock in hollow heart? Once split in half, one can discover a set of rock crystal (or white quartz) which forms what is called a geode.
Quartz geodes are perfect for cleaning / purifying your other crystals. The rock crystal has a role of transmitter, amplifier and receiver. This geode can amplify the powers of your stones while cleaning them with their negativity.
It is also excellent to harmonize the energies of your home, develop your intuition / clairvoyance / mediumness or divination.