BH250-74
Title
BH250-74
Subject
Cummingtonite Schist
Description
Major Mineral: cummingtonite,
Minor Minerals: biotite, chlorite
Aggregate Texture:
Cummingtonite commonly forms schistose textures resulting from the alignment of its elongated, prismatic grains along foliation planes. In fine-grained samples, it may exhibit a fibrous or lamellar habit. When viewed in thin section, grains cut perpendicular to the c-axis clearly display the characteristic amphibole cleavage angles (~56° and 124°).
Compare the cummingtonite in this thin section with those in BH250-246.
Minor Minerals: biotite, chlorite
Aggregate Texture:
Cummingtonite commonly forms schistose textures resulting from the alignment of its elongated, prismatic grains along foliation planes. In fine-grained samples, it may exhibit a fibrous or lamellar habit. When viewed in thin section, grains cut perpendicular to the c-axis clearly display the characteristic amphibole cleavage angles (~56° and 124°).
Compare the cummingtonite in this thin section with those in BH250-246.
Coverage
Location: Lead, South Dakota, USA
Creator
Bereket Haileab
Source
From the rock collection of Bereket Haileab. Sample BH250-74. Housed at Carleton College in Minnesota.
Type
Thin section and hand sample
Relation
Collection
Citation
Bereket Haileab, “BH250-74,” BH250 Mineralogy Teaching Collection, accessed April 25, 2026, https://bereket-haileab.geology.sites.carleton.edu/items/show/84.