Royal Austrian Mail Stamp - Help!

Hello!

I'd like to find as much information as possible about the following stamp:



I've found this stamp at home. All I was able to deduce from it it is that it was issued before 1898, since this date is stamped on it. SO it is older than 114 years. Browsing through the Internet I found out this page

http://www.old-stamps.com/stamps/au...st_1381.html

where the only relevant piece of information seem to be that it was used for the Royal Austrian mail.

Since I am not a stamp collector I am wondering,where could I find more information about it I(perhaps writing to someone?) ?Moreover,does it look like a rare stamp? I am asking this because I am wondering if I should keep more care of it? (I found it in a book,and perhaps I should place it in a more "safe" environment)