What's wool made of?

For example, silk is made of [fibroin](https://en.wikipedia.org/wiki/Fibroin). But what's wool made of?




Unlike silk or cotton, wool does not have a homogeneous structure. Its core is considered to be made of [keratin](https://en.wikipedia.org/wiki/Keratin), a generic type of protein found in human hair and epidermis. A detailed PDF on Merino wool can be downloaded from [here](http://www.csiro.au/~/media/CSIROau/Divisions/CSIRO%20Materials%20Science%20and%20Engineering/WoolStructure_CMSE_PDF%20Standard.pdf). 


Thanks for encouraging me, through your question, to read that PDF, which explains both the chemical and physical properties in a straight-forward fashion.


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