accessing instance of a script

Hello,

I wrote the following script to store the initial position of few gameobjects. The script is attached to each gameobject :

 using UnityEngine;
 using System.Collections;
 
 public class ProprietePieces : MonoBehaviour
 {
     public static Vector3 PositionInitialePiece;
    
     // Use this for initialization
     void Start()
     {
         PositionInitialePiece = gameObject.transform.position;
     }
 }

My problem is that I do not succeed to access the "PositionInitialePiece" variable from another script. Here is what I use :

  ProprietePieces ScriptProprietePieces = gameObject.GetComponent<ProprietePieces>();
     
  Debug.Log(ScriptProprietePieces.PositionInitialePiece);

I get an error message saying that "Member ProprietePieces.PositionInitialePiece is not reachable with an instance reference, use a type name"

I do not understand what is the problem, and hope someone could help me.