a vein of gold的用法和样例：
- A vein of gold was seen cropping out.
- There is a vein of melancholy in his character.
- With axe and shovel you explore this mine, and follow the marrowy store, yellow as beef tallow, or as if you had struck on a vein of gold, deep into the earth.
- There is a vein of humor in his nature.
- A vein of copper was seen criopping out.