Amethyst's definition in its original language is "not intoxicated." Your judgment is impaired when you're drunk.
Amethyst, then, provides clarity and perhaps the insight you require to see things clearly.
This combines with the stone's relaxing influence to make it a great study and learning crystal.
This brings up the reason amethyst is a lucky stone for Taurus once more. That's because it makes the mind more clear.
Although the Taurus is tenacious and diligent, stubbornness is one of their greatest flaws.
Amethyst can aid Taurus in getting through their own stubbornness, which brings good fortune to the bulls.