What constitutes a variety as in Grossular var. Hessonite?

Can someone please explain why this seemingly arbitrary distincion is made? I can find no information on Google -- other than that the Hessonite garnet is the Jyotish :X gem related to Rahu :X (Moon's ascending node :X), which is mainly an elemental and instinctual entity :X :X :X ...

OK, I think I'm okay now.

Anyway, the hessonite page on MinDat gives no details other than a picture. Wiki, offers nothing; RUFF doesn't have an entry.

TIA/John

Hessonite is a name for gemmy garnet, particularly grossular (the orange to yellowish material). It is commonly used in the gem trade, and frequently misused by novice collectors (i.e. labeling an opaque grossular 'hessonite').

Best to avoid such useless varietal names.

Yeah, I'd agree--but mindat itself makes a point of listing it--but then doesn't give the basis for making the distinction...

As a degreed geologistand and avid collector, trade names irritate me. I usually spend several minutes googling a new mineral I have never heard of only to find out its a sexy trade name for some gemstone. I don't really blame novices as who would want a stone called corundum or feldspar? Doesn't Ruby and Moonstone sound much more exciting?

"Hessonite" is a +/- orange grossular (orange due to iron content), thus a very loosely defined varietal name.
As Philippe said, best avoid it and use grossular instead.

Hessonite is not just an orange garnet nor just a gem quality one. At least, Gemologically speaking.

Hessonite is the Ugrandite/Grossular family of garnet, Ca₃Al₂(SiO₄)₃, known for its roiling or heat wave effect inside. It is also known as the "cinnamon stone" & Hyacinth Garnet.

Hessonite ranges in color from red to orange to yellow and everything in between, as in mixtures of those three colors due to its chromophore being iron.

Hessonite also can often show bands around 407nm and and 430nm, but not always.

So, basically, any Grossularite garnet in the colors(or combos of) red, orange, or yellow, is considered a Hessonite garnet. Aka, those colors caused by iron being the chromophore. "Hessonite" is just the name given to those colors, caused by Iron, in the gem trade, be it gem quality material or totally opaque material(clarity has nothing to do with the name).

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