A modern 1N34 or = diode will be as good or better (and a lot less trouble) than an early galena crystal where you scratch around with a catwhisker. Many different schemes were tried like double galena etc. but didn't prove to be any more sensitive than one good chunk of rock. However, a good piece of galena and a period-correct detector is fun to operate and is a trip back in time. Here are some pictures of various old and new galena/catwhisker setups:
http://www.google.com/search?tbm=isc...1489l1.11l12l0
And here are some raw parts for building your own detector stand:
http://www.google.com/search?tbm=isc...1489l1.11l12l0
You can buy the already mounted galenas as shown. I have also bought a hunk of galena about the size of a golf ball from a rock shop and it has a lot of hot spots on it and would yield enough to make dozens of detectors.