ArgumentOutOfRangeException: Index was out of range. In a List<List<GameObject>>

i was trying to make a List of different kinds of gathering blocks. But i wanted to make it so that there was only 1 in the inspector and then seperate them by category in code. I wanted to do this so the inspector did not get cluttered with different lists.

However after setting it up, i kept getting a error saying ArgumentOutOfRangeException: Index was out of range. Must be non-negative and less than the size of the collection.
> Parameter name: index
System.Collections.Generic.List`1[T].set_Item (System.Int32 index, T value) (at <9aad1b3a47484d63ba2b3985692d80e9>:0)
BlockPlacing.Start () (at Assets/m/Scripts/BlockPlacing.cs:16)

My code/inspector list looks like this:

Inspector List Image

Code:

    [SerializeField] private List<GameObject> blocks = new List<GameObject>(64);
    private List<List<GameObject>> _mineralsList = new List<List<GameObject>>(4);

    void Start()
    {
        for (int j = 0; j < 4; j++)
        {
            for (int i = 0; i < 4; i++)
            {
                _mineralsList[j].Insert(i, blocks[i]);
            }
        }
    }

A different way of adding to the _mineralList i saw and tried was _mineralsList[j][i] = blocks[i] But that also didn't work and gave the same error.

try to use this code:

public void Start()
{
	for (int j = 0; j < 4; j++)
	{
		_mineralsList.Add(new List<GameObject>());
		for (int i = 0; i < 4; i++)
		{
			if (i < blocks.Count) {
				_mineralsList[j].Add(blocks[i]);
			}
		}
	}
}