Quartz, var. Amethyst
Posted by: macadmin on 04.14.2020 | Filed under:

Quartz, var. Amethyst

Specimen # 102293
Mineral: Quartz, var. Amethyst
Location: Mamuju area, Sulawesi Barat Province, Sulawesi, Indonesia
Size: 7.1 x 5.3 x 2.5 cm


Detailed Description

This plate of darker purple-bluish amethyst hosts lighter, lilac-coloured amethyst balls. Both the balls and the background plate are lustrous and sparkle brightly. The amethyst balls are colour-zoned, with light purple centres, grading to almost colourless quartz at their edges. There is one small wheat-sheaf-like aggregate of quartz, beautiful under magnification. The bluish look to the underlying amethyst is likely caused by small amounts of included celadonite. In excellent condition, no damage, one tiny contact if you search for it. Striking, the contrasting balls and background, and nice with the zoning.


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.