The Book of Enoch includes many chapters which have been added later, so one has to be careful, to correctly deduce which passages are the original ones
Dead Sea Scrolls forgeries:
http://breakfornews.com/forum/viewtopic.php?p=30145#30145
A Mysterious Metal
One of the best-kept secrets of the Dead Sea Scrolls has been the discovery of metals in the black ink. That finding was buried in unpublished results, and wasn't unearthed until 1996. The presence of metals further points to the scrolls being of medieval origin.
Scientific testing of the scrolls in the early 1950s found silver, manganese, iron and other metals in the black ink used on the scrolls. Scholars tried to downplay the discovery of these metals by saying that some of them, like copper and lead, were byproducts of leaching from a bronze inkwell. Yet silver, manganese and iron are not components in the making of bronze. The 1990s tests also detected the presence of strontium and titanium but could not tell if they were pure. (In its purest form, neither element was isolated until the 1800s.)