GCN just dropped an infomercial about some brand new magnesium bike (Gravel). They say the frame weighs about 1100 g + all the usual marketing terms (stiff, responsive… yadayadayada). It retails for 2500$, which seems fair, given the weight and specs…
Now where are the material science nerds that can tell me, what’s the catch with magnesium and why virtually nobody is using it as frame material 
Don’t go out in the rain 
Magnesium frames were a thing back in the day. The tour was even won on it (retrospectively) in 2006.
It’s only recently that some of its shortcomings have been overcome with more advanced alloys, so my guess is that companies are quite heavily invested in carbon and aluminium production, making a transition expensive.
Mike
Its to do with corrosion. Magnesium corrodes in a strange way, I can’t quite remember, but it makes it bad as a frame material. There’s a lot of research going on to find a magnesium alloy that will do away with this weakness, because otherwise it would be fantastic as a material.
No idea about this frame, maybe they’ve found something.
KIRK Revolution mountain bike. I snapped two frames at the head tube, dropping the front wheel off a kerb. Things might have moved on but I’d be in no hurry to go back there.
Did you go to their website?
Also, from a financing perspective, I don’t have great confidence in that company.
Yeah, in that GCN video they spent a whole lot of time talking about special alloys and coating to prevent corrosion… but indeed that did not inspire confidence. I wouldn’t want to be a testbunny for those frames as well, there are really enough frame materials to chose from already, that are well tested 
What’s the benefit over current frame materials?
I think that hits the nail on the hat… not much benefit it seems.
One thing they highlighted though, was the environmental impact. Apparently it requires much less energy to produce a Mg bike compared to other materials (And as most metals, Mg is fully recyclable). So maybe they just try to carve out a niche for the environmental conscious cyclist in an extremely crowded and competitive field of frame manufacturers