Putting it here so I don't have to type it out all official like.
Tanzanite is a very bold blue (at times with a slight purple hue) gemstone, with a moderate value as far as gemstones go. It is found only in the foothills on the south side of Mount Kilimanjaro. This relative scarcity has caused some prices to increase, and much of it has been mined out as of the in game year. It is a soft and brittle, so if you drop it, there is a chance it can crack. It's only real value is in making jewelery.
As far as it's relationship to the Maasai, it was initially discovered by one of their tribesmen in 1967. As such, it has no inherent spiritual link with their people, at least in a traditional sense. I am sure some of them have used it for ornamentation however. If they are actually using it for some other purpose now, that information isn't available on the matrix, and it would be a very recent development. So I think its safe to say the stone isn't sacred, but it may have (or not) some quality that they are using now.
And thus ends learning time for today
