a jeering gargoyle  

This gargoyle killed my level 65 SK!

These Gargs are the easiest, and the best ones to hunt, unless you are in a large or high lvl group. If you can get an invis (an enchanter is best for this, as they will probably be wanting the rune of fortune that Enynti drops, and she spawns right by the gargs roosting place) and get to the roost/ledge just past and under the entrance to the castle, then that is the perfect palce to pull them to. There is usually only 1 wanderer that passes that location, and it's normally a herald or usher, so not too many problems taking that out.
Mezzing/harmonying/soothing the gargs and Enynti and pulling one at a time is the best way of handling them, but all 3 can be taken at once in an emergency, as long as you have at least one tank and/or someone who can heal well. The spawn rate is about 15 mins I think, so if you find yourself with mana to spare, you can try to pull some of the heralds/ushers and such by the castle entrance, but beware of a train forming if you are not careful about it. The drop rate of granite is about 1 in 4, or at least it was when I was there, so an hours garg killing should get you at least 3 pieces, if you are lucky.

"Pain is your best friend, it reminds you that you are still alive"

as stated above, these are one of the gargs that drop the granite.

they are also the EASIEST garg that drops the granite.

they are also the ONLY garg that drops granite that spawns OUTSIDE of the castle (i.e., the Eentyi spawn point)

catch my drift? camp there for your granite, unless you have the group to go inside.