Staurolite

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Twinned crystals of staurolite measuring to 7.0 cm in size embedded up on a schist matrix. In great condition, this is excellent for the species. Collected in the 1990s.Pestsovye Keivy in the Keivy Mountains of the Lovozersky district, Murmansk Oblast, Russia, has no specific historical records of formal opening or closing dates because it is a regional metamorphic mineral collecting area and scientific study site rather than an active commercial mine. Geologically, the area is part of the Keivy domain within the northeastern Baltic Shield, consisting of Precambrian high-alumina sedimentary protoliths that underwent regional metamorphism under amphibolite- to granulite-facies conditions to form silvery muscovite-quartz-rich schists. The locality is world-famous for its remarkable staurolite porphyroblasts, which frequently occur as distinct reddish-brown to dark brown penetration twins forming 60-degree X-shapes or 90-degree cruciform crosses embedded directly within the glittering mica schist matrix.