What were Daguerreotypes made of?

Daguerreotypes were made of copper plates coated with silver. The plates were dipped in an iodine fluid, which created the silver-halide "silver iodide." Silver halides are silver molecules bonded with halogens (elements that end in "-ine"). Silver bromide and silver chloride are also silver-halides. Why make a silver-halide? Because these compounds have a property of photosensitivity (light sensitive). As this coated plates dried, they were exposed to light, hence the reason for the silver compound. Afterwards, they were coated again, this time with Mercury heated to 75 degrees Celsius. Finally, they are put in salt water to finish (this part I don't know why it's done...). The final picture was usually put in a glass case to protect it; oils produced by the skin can cause copper to corrode.

I hope this information was helpful. If you need more information, feel free to let me know.