Many people picture the crust as being like the skin on an orange, but it is much more like the skin on an apple. Fusion crust is very thin, usually less than 1mm thick. It is generally the thickness of a heavy piece of paper. Out west it is many times confused with desert varnish which is a dark coating on rocks exposed to the sun and elements for a long time. Below are pictures that show both.
Most meteorites contain large amounts of iron and as a result are attracted to a magnet.
This is not definitive because some meteorites are not attracted to a magnet and many earth rocks are. However, it is another clue for separating the trash from the treasures. If the interior of the meteorite is visible, there are a couple clues. If it is an ordinary chondrite it will have small flecks of metal. The flecks may not be visible on a broken weathered surface, but if you grind a fresh surface they will be visible except for extremely weathered chondrites.