https://www.slideshare.net/anasarhihou/cours-de-mineralogie-chap4-fin-silicates
https://books.google.fr/books?id=JV87AAAAcAAJ&pg=PA503&lpg=PA503&dq=humboldilites&source=bl&ots=fSln8leq9h&sig=jFlLhEtDPnjurAo94cc691hTGX4&hl=fr&sa=X&ved=0ahUKEwjZpojgu7HSAhULuRQKHe-JDksQ6AEIMjAG#v=onepage&q=humboldilites&f=false
