I am taken from a mine and shut up in a wooden case. When I am needed, I am thrown away. What am I?

The answer is "a pencil!"

Explanation: 📝 Imagine a pencil being taken from a mine where graphite is found, and then it's placed inside a wooden case – the pencil itself! When we need to use the pencil, we sharpen it, and as we do so, we throw away the shavings. Those shavings are what we needed and used! 😄🎉 So, the pencil is playfully teasing us, saying "Hey, you only need me for my shavings! But don't worry, I'll be here whenever you need to jot down something!" 📏✏️