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.
When a virtual machine is running, its window is the active window and a USB device is plugged into the host computer, the device automatically connects to the guest instead of the host. This autoconnect feature can be disabled in the USB Controller panel of the virtual machine settings editor (VM > Settings).