Agate (Grape Chalcedony)

Grape Agate is a botryoidal formation of purple chalcedony-ish material. Most specimens have a relatively rough texture along the outside, rather than being perfectly smooth. Some specimens also come in green, and bi-color specimens are highly prized. This mineral is a rarity, and only recently discovered. Grape Agate seems similar to amethyst at first glance, but the spheres themselves are actually microcrystalline quartz that grows radially rather than the macro crystals that characterize quartz varieties like amethyst.

They’re a bit hard to define, but they’re neither chalcedony nor classic amethyst crystals. The term usually used for this form of silica is amethystine. The coloration of grape agate appears to come from some form of clay inclusion, although it’s also been said to have the same coloring agent (ie: iron) as amethyst. The green varieties come from a different inclusion in the clay, and there are also many specimens with minimal coloration. Grape Agate isn’t actually an agate.

There is no internal banding, and the stones are comprised of relatively pure silica without the plume, moss, and other inclusions common in agates. The name has stuck regardless. Grape Agate is graded by coloration for the most part. Bold colors tend to command a higher price, as do larger specimens. Note that, like amethyst, grape agate will begin to lose color after extensive sun exposure.

Grape Agate is actually found in only one place in the world. The Manakarra Beach in Indonesia appears to be the first place that miners discovered it, shortly followed by a minor rush of people trying to get more of it. The material was instantly recognizable as being unique, which is rare for a modern mineral discovery. The material was originally sold as Manakarra Grape Agate before the trade name simply became Grape Agate. The Beach is in Western Sulawesi, an island in Indonesia.

It appears that the material first showed up on the market in about 2016. Usually, when we refer to “recent” mineral discovery, we’re talking about in the past 40 years but in this case, it’s a very recent addition to the trade.