BH250-4
Title
BH250-4
Subject
Kyanite Quarzite
Description
Major Minerals: quartz, kyanite, muscovite, calcite, olivine
Minor Minerals: serpentine, rutile
Optics: bladed, long prismatic, perfect cleavages, cross parting with 85 degrees
BH250-4 is a kyanite quartzite, a high-grade metamorphic rock composed predominantly of quartz and bladed kyanite, with minor amounts of muscovite. The presence of kyanite indicates metamorphism under moderate to high pressure and elevated temperatures, consistent with the kyanite stability field and typical of Barrovian metamorphism. This suggests the rock was buried to mid-crustal depths.
The kyanite crystals exhibit a distinct bladed habit, often aligned with the rock’s foliation. The protolith is confidently interpreted as pelitic, originally an aluminum-rich sedimentary rock such as a mudstone or shale, which underwent recrystallization and mineralogical transformation during regional metamorphism.
Minor Minerals: serpentine, rutile
Optics: bladed, long prismatic, perfect cleavages, cross parting with 85 degrees
BH250-4 is a kyanite quartzite, a high-grade metamorphic rock composed predominantly of quartz and bladed kyanite, with minor amounts of muscovite. The presence of kyanite indicates metamorphism under moderate to high pressure and elevated temperatures, consistent with the kyanite stability field and typical of Barrovian metamorphism. This suggests the rock was buried to mid-crustal depths.
The kyanite crystals exhibit a distinct bladed habit, often aligned with the rock’s foliation. The protolith is confidently interpreted as pelitic, originally an aluminum-rich sedimentary rock such as a mudstone or shale, which underwent recrystallization and mineralogical transformation during regional metamorphism.
Coverage
Location: Ogilby, California, USA
Creator
Bereket Haileab
Source
From the rock collection of Bereket Haileab. Sample 4. Housed at Carleton College in Minnesota.
Type
Thin section and hand sample
Relation
Collection
Citation
Bereket Haileab, “BH250-4,” BH250 Mineralogy Teaching Collection, accessed April 25, 2026, https://bereket-haileab.geology.sites.carleton.edu/items/show/4.