Rutile Paramorph After Brookite
Small Cabinet, 5.7 x 5.4 x 4.8 cm
Magnet Cove, Hot Spring County, Arkansas

Undoubtedly an old specimen, this piece is typical of a size and style said to be found here in the very early days, late 1800s to early 1900s. I have seen only a very few rutile specimens even approaching this size (in the Smithsonian and American Museums), and its degree of preservation and perfection is shocking (it is pristine and complete all around!). I have seen no brookite of this size, period, from here. This is a kind of pseudomorph replacement called a paramorph, now. It is no longer a brookite despite its apparent habit: A paramorph (also called allomorph) is a mineral changed on the molecular level. The mineral looks identical to the original unaltered form of the brookite (which is normally orthorhombic and not as heavy or robust as rutile) but is now replaced by another form of natural titanium oxide, (tetragonal) rutile. This is, I think, a MAJOR US locality specimen and a major rutile by any worldwide standard