Detailed Description

This specimen has superb form, lilac balls joined in branching clusters. Good silky lustre. The piece is a floater, with no points of attachment. This piece hosts a few very small second-generation quartz growths that, under magnification, exhibit a crystal habit a little like the wheat-sheaf form of stilbite (these are at the side and on the back of the specimen). In excellent condition, no incomplete balls and no damage, a couple of tiny points of contact from small missing balls – you have to examine the piece searching for them to find them – this is superb, top quality. For my taste one of the nicest specimens of Mamuju grape amethyst I’ve seen.

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.