Changing array materials on collision (c#)

Hi all, I am having a bit of trouble getting individual objects in an array to change their material on collision. The problem I am having is that this happens across the array and not just to specific blocks. The first collision works correctly, but if i then collide with an un-hit block, its material skips to the secondHit material or thirdHit material (if 2 different blocks have been hit previously).

As you can see i am also changing mass on collision, this seems to be working fine, which just adds to my confusion.

How can i get the individual blocks in the array to hold their own hit value? I thought using a foreach loop would fix this.

any help would be brilliant, thanks in advance! A.

 public Material firstHit;
 
 public Material secondHit;

 public Material thirdHit;

 public static int hitNumber = 0;


 void OnCollisionEnter (Collision collision)

 {
     foreach (GameObject block in BlockCount.blocks) {
 
                if (collision.gameObject == block) {

             block.rigidbody.mass = block.rigidbody.mass / 2;

             hitNumber++;

             print(hitNumber);

             if (hitNumber == 1) {

                 block.renderer.material = firstHit;

             }

             if (hitNumber == 2) {

                 block.renderer.material = secondHit;

             }

             if (hitNumber == 3) {

                 block.renderer.material = thirdHit;

                 hitNumber = 0;
             }
         }


     }

 }