Public Transform Is Not Showing Up?

I am trying to get a transform to be created and this is my code but the transform isn’t showing up in the inspector but the textures are.

#pragma strict

var grass : Texture;
var stone : Texture;
var block : Transform;

function Start () 
	if (transform.position.y == 1)
		Instantiate (block, Vector3(0,-1,0), Vector3(0,0,0));

Original Answer:

You need to instantiate a GameObject, not a transform.
Transforms cannot exist without a GameObject

Updated Answer:

a transform’s rotation is stored as a quaternion, not a Vector3.

You can set a transform’s rotation from a vector3 like this:

myRotation : Vector3 = Vector3.up;
transform.rotation = Quaternion.Euler(myRotation);