Gui Box - Texture - Spritesheet

So, I have a box which i want to add a sprite(image) to it instead of text. But it needs a texture.

I've done this: (model is a gameObject)

 spriteRenderer = model.GetComponent<SpriteRenderer>();
  iconTexture = spriteRenderer.sprite.texture;

My only problem here is that the model is using a spritesheet and when i call iconTexture I get the whole spritesheet and not just the first frame of the sSheet. Is there any way to access just one frame of the spriteSheet?

Thanks for your time and help! have a good one.