Looks to have some similarity to the frame in this post: viewtopic.php?f=6&t=267491
Nothing like, this one's steel, that's aluminium.
I have a similar, unknown steel frame: http://www.retrobike.co.uk/forum/viewto ... p;t=232089
. I still don't know exactly what it is, but I've given up worrying about it, I like the layout of the frame, top routed cables etc., it rides nicely and I think it looks pretty nifty in its new metallic green finish.
Thing is, dozens of major brands were having TIG welded steel built in Taiwan in the 90s, Marin, Kona, Scott, etc. and details like drop outs, cable stops, canti bridges etc., were often very similar. To add to the confusion, smaller, lesser known brands and possibly some shops could have similar "own brand" frames built in the same factories and badged up with slight detail variations, different cable routing, drop outs etc., so you might never know what it is.
Weight might give you some idea of quality, if it's under 2,000g, it's light for a steel frame and it would have to be made of a decent quality thin wall tube. 2,000 to 2,500g is still pretty light and would probably be made of something double butted. As a reference, my 19" Marin Pine Mountain, made of Tange double butted tubes weighs in at 2,560g, my unknown frame, made from Tange Ultimate Ultrastrong weighs 2,235g. If it weighs over 3,000g, it's probably not made of anything special, but having said all that, it's a big generalisation, best thing is to build it up, ride it and see if you like it.