Copper and Credit

Sample: A block of thermitic copper
Source: Me.

A thermite reaction is defined as the reduction of a metal oxide with a reactive metal, in this case copper(I) oxide (Cu₂O) with Aluminum metal. It produces a pulse of heat, a lot of green vapor, and leaves you with a nice puddle of boiling copper, hopefully in some sort mold.




Thermitic copper, 60x.



Thermitic copper crystalline grain, 200x. As a consequence of the... violence... of the thermite reaction, as well as the rapid cooling of the molten copper, large crystalline grains are formed. Makes the surface of the copper block look all sparkly.

Sample: Credit Card Holograms
Source: Wallet, banks.

Credit card holograms are made by making a hologram (cheap) and then etching the interference pattern into a metal stamp (expensive). The stamp can then stamp out 50,000 or so reproductions, making the $45,000 or so charge for the stamp worth it.



A credit card hologram, numbers removed for security purposes, 10x.



Credit card hologram, 60x.



Credit card hologram, 200x.



A different credit card hologram. 10x.



Credit card hologram II, 60x.



Credit card hologram II, 200x.