So some rocks are radioactive because they have radioisotopes in their nuclei. Also they may have radon gas trapped in their crystals if they are igneous rock. They could also be radioactive due to the fact that the atom of the rock is unstable.
Connecting USB Devices Manually. Choose VM > Removable Devices to connect specific USB devices to your virtual machine. You can connect up to two USB devices at a time. If the physical USB devices are connected to the host computer through a hub, the virtual machine sees only the USB devices, not the hub.
Virtual CloneDrive. Virtual CloneDrive works and behaves just like a physical CD, DVD, or Blu-ray drive, although it only exists virtually. Image files can be inserted into the virtual drive from your harddisk or from a network drive by just a double-click, and thus be used like a normal CD, DVD, or Blu-ray. Virtual CloneDrive supports up to 15 virtual drives at the same time - no matter if the image file contains audio, video or just simple data.