Answer:
I'm written with two letters, said with one and seen with two. What am I?
I am the minerals vital for your good health.
What is harder to catch the faster you run?
I start with T end with T and within me is T.
Although I may have eyes I cannot see. I have a round brown face with lots of acne.
Though not a plant, has leaves. Though not a beast, has spine. Though many wouldn't need this thing, It's more valuable than wine.