This is definitely one of "Gunsmoke"'s lesser episodes. Way lesser -- very un-Gunsmokey, a "desperation" episode. I suspect it's a first draft, knocked out over a long weekend. It shows about as much originality as a rubber stamp -- and less wit.
It apparently never occurred to the writers that Kansas was hardly known for its gold mines. And as far as I know, the gold in gold mines is usually embedded in a quartz matrix, requiring a stamp mill for extraction. But who cares about historical accuracy?
John Anderson makes another one of his appearances in what must have been a hundred TV Westerns. (My favorite John Anderson moment comes in "The Rifleman", when he's mauled by a stunt man in a bad bear costume.)
Some of Pickaxe's buildings more resemble the Southwest than Kansas. And as it has a house of ill-repute, why is Kitty so overwhelmingly attractive? It must be her insistence on dressing like Jennifer Marlowe. Who in their right mind would visit a gold mine dressed like that?
There are two good moments. When Matt asks Doc "Don't you have some patients to take care of, or uh maybe a sick cow, or sumpin'?" and Doc eyes Festus, Festus' reaction is priceless. And when Kitty says "If you say 'I told you so!', I'll never talk to you again!", Matt's reaction suggests that maybe it wouldn't be such a bad thing.
We also learn that Kitty, like Indiana Jones, is afraid of reptiles. In this case, lizards.
The whole thing is reminiscent of an "Adventures of Superman" episode. You should have no trouble deciding who's who.