It's fairly rare in the wild, but does exist. I want to say it's mostly in Egypt, but it may be in the other countries, too.
The only one I have ever found in the wild, I found in Egypt on the shores of the river near the pyramid.
And now to dispatch with this silly rumor, once and for all:
I waited with much anticipation for WA, and bought it the day it came out. The first place I traveled to was China, and I bought everything I could buy there shortly before I went home. Martial Arts became my absolute favorite skill to train instantly (before I discovered Nectar Making, and subsequently Photography lol). After maxing the skill, I set about achieving all the skill challenge, and board breaker was the first. I found a lot of gems, and Tiberium was one of the first. At first I couldn't cut it, so I carried it around for a while (and it
doesn't make you sick if it's not cut btw), but after finding a bunch of gems, the spiral cut finally came up while I was mailing out gems. So I shipped it off.
This was long before I knew anything about transfiguriation, so all I was doing was displaying them in the house. I thought the spire cut was kinda neat, so it got a place of honor by itself on the coffee table in the living room. Of course, it grew in a couple of days...but it was a long time before I realized that this made it increase in value, so I left it there.
It sat on that coffee table for
3 generations, and it didn't duplicate.
So not only does it no longer duplicate, it never did in the first place.