THE LEMURIAN SEED CRYSTALS
Written by Katrina Raphaell
Raphaell recounts that a particular cluster were in fact found in Brazil. There is also a number for a Canadian New Age bookstore on the pdf article, who may in fact know the author, or can tell you a source from the actual book.
I've also included a link to the Lemuria legend, where you can find the hypothesized location, and more sources. It would make sense that the hypothesized location would have the greatest cluster of these crystals. However given continental drift, and oceanic currents, they may show up in odd places as well.
Hope this helps,