Answer:
I am the ultimate killing machine used not once but TWICE I can be made by humans.
I go up and down at the same time. Up towards to sky and down towards the ground
As a state in America I am round on both sides and high in the middle.
I go around in circles, but always straight ahead. Never complain, no matter where I am led. What am I?
I beam, I shine, I sparkle white. I'll brighten the day with a single light. I'll charm and enchant all. I'll bring the best in you all. What am I?
It flows out of the soil, It burns you if it boils, And holds us in its coils, More valuable than gold, As black as it is old.