This amethyst does look like a bunch of grapes. The lilac amethyst balls have nice separation and form, and a matte lustre. The specimen is a floater, complete all-around with no points of contact. In excellent condition, a couple of incomplete balls and a tiny spot where a ball is missing. A sweet specimen.
About These Indonesian “Grape Amethyst” Specimens
Originally referred to as “grape agate”, specimens were first found in the Mamuju area in 2015. These specimens are recovered from clay, in the spaces between the “pillows” in pillow lava. Although they were first known as “grape agate”, they are not cryptocrystalline (and therefore are not agate) – they are balls of radiating crystalline quartz. When the find first came to market, there was a large amount of material, much of which was poor quality. With the passage of time, the diggers began to produce higher quality specimens. The recent article on this material in the Mineralogical Record (Nov-Dec. 2018) observes that the production of fine specimens is beginning to decline, although there are still a few very active teams working the deposits. The article speculates, based upon local sources, that all specimen mining of the pillow lava deposits will likely cease within the next three to four years. As with all mineral specimen localities, the ultimate accuracy of such speculation varies. In this case, the limited geographical extent of the known pillow lava deposits is a key factor.