spent 4 hours mining amethyst on wed. had 2 3x3 titanium hammers i forged, 1 1x2 titanium hammer, and 2 stacks of iron hammers. strip mined a large area for amethyst lit up on atlas. ended up with 99 amethyst, 400 silver, 100 gold.
similar results when i went mining for diamonds last week.
To me that seems like crappy amethyst yield.