Mercury thermometer break

Hi everyone, I broke my thermometer while walking outside (on stairs) it broke and half percent of mercury (quicksilver) splitted from it to the ground. I couldn't gather and pick up them because they were very tiny and the surface was rugged. I put thermometer in the plastic bottle and recycle it. But I couldn't picked up splitted mercury beads from the ground (outside of my house) and I simply sweep the area to the flower-ground. Give suggestions is it harmful? 

Google it or I think the fire department can advise you about materials being hazardous or not.  Contact them.