I have 11 stacks of marbles, each stack consisting of 10 marbles. I am also given a digital scale with arbitrary precision. All of these marbles are indistinguishable.

Given that all the stacks of marbles are made of glass weighing 10 grams each except one stack which are all made from clay but still looks like glass. A clay marble weighs 9 grams.

What is the minimum amount of weighing needed such that you can identify the stack containing the clay ones?