Starting in a corner of the room, cover a two-foot square area with mortar. Use a trowel to apply a two-inch deep smooth layer of mortar on the ground.
Cover the back of a rock with a thin layer of mortar. Use a trowel to apply the mortar to completely cover the back of the rock.
Firmly set the mortar-covered side of the rock into the mortar bed. Lay a level on top of the rock to determine how level it is. If the rock is unlevel, bang a mallet on the surface of the rock that is sitting higher until the rock is level in the ground.
Continue the process of adding rocks to the floor, following the instructions in steps 2 and 3. Use your creativity when adding rocks to the floor, fitting in different sizes and colors in locations that you think look visually appealing.
Fill the gaps between the rocks with mortar. Use a trowel to work the mortar between the gaps in the rocks.
Wipe the mortar off of the surface of the rocks with a damp sponge. Allow the floor to set for 48 to 72 hours.