Star rose quartz from Madagascar
29th Mar 2019 16:20 UTCTony Albini
From my experience, the source of these "star rose quartz" are not from one single ocality , but many, most of them are located in the Vakinankaratra Region in the center of Madagascar (as the one in the photo above which is found in one of the pegmatites on the border of Vakinakaratra and Amoron'i Mania Regions).
Among the most famous localities were rose quarts are/were mined are Ialamitana, Tsaramanga, Samiresy to mention a few. Not all rose quartz found at these localities are showing asterism though.
As for the photo of the rose quartz uploaded with Didy as locality (se below), the locality is based on a label from an old collection, and said to be collected by a french prospector/geologist. So it may be uncertain. I am not familiar with any quartz rose localities in this area (but they may of course excist). The quartz rose in the photo looks like a normal rose quartz to me, not showing any asterism.
BTW, Did you know that the cause of the rose coloration in rose quartz is caused by nanosized inclusions of fibers, 0.1 to 0.5 μm, of dumortierite or a dumoriterie like mineral? The oriented fibers forming the asterism are probably of the same material.
See article:
https://www.its.caltech.edu/~chima/publications/2001_AM_rose_quartz.pdf
Didy, Ambatondrazaka District, Alaotra-Mangoro, Madagascar