Xanthitane is a very uncommon varietal name (not listed on Mindat) for this anatase and is very rare and very unusual. It is a soft, friable, yellow earthy material as alteration pseudomorphs after titanite. So, this is a specimen of anatase (xanthitane) pseudomorphing two titanite crystals. In this particular tan, flattened, thumbnail, you can see the sharp edges of two, parallel-growth, pseudomorphed titanite crystals on the left side of the specimen. Personally, I have never heard of or seen one of these before. Ex. Dick Jones Collection, who probably collected this material in the Jones Mine in the 1960s or 1970s.