Simulations / Models / and Analogues.

Simulations: the imitation of the operation of a real-world process or system over time.


Models: A systematic description of an object or phenomenon that shares important characteristics with the object or phenomenon.


Ex: Our crystal formations,


Analogues: A compound with a molecular structure closely similar to that of another.



Igneous: 

https://www.geology.ucdavis.edu/fun/geologyrocks/mondavi.html

 
Metamorphic: Foliate (has bands and stripes) . 

 

http://photoseek.photoshelter.com/image/I0000aNDGKXxR0o0

 A representation:

http://www.blisstree.com/2009/02/10/food/review-nestles-butterfinger-buzz/

Sedimentary:

http://teachmehowtoclassify.blogspot.com/p/sedimentary-rock.html