Some builders used to use a technique to see if the planned construction was going to be on a fairy path; they would map out the floor plan in the earth and place a pile of stones at each corner and leave it overnight, if the stones were undisturbed it was safe to build, otherwise the work would not continue. There is another theme that states if one's house is on a fairy path, one must leave the doors and windows open at night, front and back, to allow fairies to pass through. Builders were also advised against using white quartz in their stonework, as it is said to be a fairy stone.