BH250-128c
Title
BH250-128c
Subject
Dolostone
Description
Major Mineral: dolomite
Minor Minerals: pyrite, orthoclase
Mineralogy Comments: majority of intergranular components are K-feldspar
BH250-128c is a dolostone sample from the base of the Platteville Limestone, specifically mapped as the Hidden Falls Member. This unit is characterized by a blocky to massive texture and a distinct conchoidal fracture, which aids in its field identification. Its rich clay mineral composition contributes to a recessive weathering profile, as seen in the outcrops around Sogn and many bluffs and roadcuts near the Twin Cities.
Lucille Baker-Stahl, Class of 2022, conducted her senior comprehensive research on this outcrop. Her study includes a wide range of photomicrographs, scanning electron microscopy (SEM) imagery, and geochemical analyses, which collectively provide insight into the mineralogy and diagenetic evolution of the Hidden Falls Member. Many of the photomicrographs reveal clear evidence of dolomitization, with textures showing relict calcite cores surrounded by dolomite rims indicating partial replacement during diagenesis and pointing to complex fluid-rock interactions during burial (EDS maps).
Minor Minerals: pyrite, orthoclase
Mineralogy Comments: majority of intergranular components are K-feldspar
BH250-128c is a dolostone sample from the base of the Platteville Limestone, specifically mapped as the Hidden Falls Member. This unit is characterized by a blocky to massive texture and a distinct conchoidal fracture, which aids in its field identification. Its rich clay mineral composition contributes to a recessive weathering profile, as seen in the outcrops around Sogn and many bluffs and roadcuts near the Twin Cities.
Lucille Baker-Stahl, Class of 2022, conducted her senior comprehensive research on this outcrop. Her study includes a wide range of photomicrographs, scanning electron microscopy (SEM) imagery, and geochemical analyses, which collectively provide insight into the mineralogy and diagenetic evolution of the Hidden Falls Member. Many of the photomicrographs reveal clear evidence of dolomitization, with textures showing relict calcite cores surrounded by dolomite rims indicating partial replacement during diagenesis and pointing to complex fluid-rock interactions during burial (EDS maps).
Coverage
Location: Warsaw Township, Minnesota, USA
Nearby Geographic Feature: Sogn Valley
GPS Coordinates: 44°24'16.8"N, 92°55'38.3"W
Nearby Geographic Feature: Sogn Valley
GPS Coordinates: 44°24'16.8"N, 92°55'38.3"W
Creator
Bereket Haileab
Source
From the rock collection of Bereket Haileab. Sample BH250-128c. Housed at Carleton College in Minnesota.
Contributor
Lucille Baker-Stahl
Type
Thin section and hand sample
Relation
Collection
Citation
Bereket Haileab, “BH250-128c,” BH250 Mineralogy Teaching Collection, accessed April 25, 2026, https://bereket-haileab.geology.sites.carleton.edu/items/show/152.