These are nice large black tourmaline crystals with terminations.  1 -1.5 inch length x 1/2 to 3/4 inch width.  See photos for size reference. 

Black Tourmaline protects against cell phones, electromagnetic smog, radiation and negative energies.  It is not only grounding and protecting working with the base chakra, but it also increases physical vitality easing stress and tension, and encouraging a positive attitude.  

Physically, black tourmaline is said to strengthen the immune system, provide pain relief and realign the spinal column.