BH250-144b
Title
BH250-144b
Subject
St. Peter Sandstone
Description
Major Mineral: quartz
Minor Minerals: iron oxide, calcite
BH250-144b is a sample from the St. Peter Sandstone, one of the most recognizable and extensively studied sandstone units in the central United States. In Minnesota, it is both geologically significant and economically important due to its purity, extent, and physical properties.
The St. Peter Sandstone is an extremely mature sandstone:
Grains are very well-sorted and well-rounded, indicating prolonged transport and extensive reworking.
Compositionally mature: Composed of ~99% quartz, with very few feldspar grains or lithic fragments.
Grain size is typically fine to medium sand.
It is often described as a supermature sandstone, reflecting multiple sedimentary recycling events and long-distance transport.
Industrial Importance
The St. Peter Sandstone is highly valued for its purity. Uniform grain size, rounded grain shape
Major Industrial Uses:
Frac Sand: The well-rounded, high-purity quartz grains make it an ideal proppant in hydraulic fracturing operations.
Glass Manufacturing: Its high silica content (~99.5%) makes it suitable for producing optical, container, and other high-quality glass products.
Cementation Characteristics
One of the defining features of the St. Peter Sandstone is its weak to moderate cementation, which enhances its suitability for industrial processing.
In most outcrops and cores, it is loosely cemented or even friable, often crumbling easily.
Exposures often feel soft and can be scratched or broken apart by hand.
Some zones are nearly uncemented, with grains bound only minimally.
Cement Types (when present): Silica (quartz overgrowths): Most common, forming thin rims on grains. Iron oxides produce reddish or yellowish stains in weathered zones. Calcite, found locally, particularly in deeper subsurface intervals.
For more information see, BH250 – Sandstone Overview with Petrographic Notes
Minor Minerals: iron oxide, calcite
BH250-144b is a sample from the St. Peter Sandstone, one of the most recognizable and extensively studied sandstone units in the central United States. In Minnesota, it is both geologically significant and economically important due to its purity, extent, and physical properties.
The St. Peter Sandstone is an extremely mature sandstone:
Grains are very well-sorted and well-rounded, indicating prolonged transport and extensive reworking.
Compositionally mature: Composed of ~99% quartz, with very few feldspar grains or lithic fragments.
Grain size is typically fine to medium sand.
It is often described as a supermature sandstone, reflecting multiple sedimentary recycling events and long-distance transport.
Industrial Importance
The St. Peter Sandstone is highly valued for its purity. Uniform grain size, rounded grain shape
Major Industrial Uses:
Frac Sand: The well-rounded, high-purity quartz grains make it an ideal proppant in hydraulic fracturing operations.
Glass Manufacturing: Its high silica content (~99.5%) makes it suitable for producing optical, container, and other high-quality glass products.
Cementation Characteristics
One of the defining features of the St. Peter Sandstone is its weak to moderate cementation, which enhances its suitability for industrial processing.
In most outcrops and cores, it is loosely cemented or even friable, often crumbling easily.
Exposures often feel soft and can be scratched or broken apart by hand.
Some zones are nearly uncemented, with grains bound only minimally.
Cement Types (when present): Silica (quartz overgrowths): Most common, forming thin rims on grains. Iron oxides produce reddish or yellowish stains in weathered zones. Calcite, found locally, particularly in deeper subsurface intervals.
For more information see, BH250 – Sandstone Overview with Petrographic Notes
Coverage
Location: Warsaw Township, Minnesota, USA
GPS Coordinates: 44°22'37.70"N, 92°55'59.25"W
GPS Coordinates: 44°22'37.70"N, 92°55'59.25"W
Creator
Bereket Haileab
Source
From the rock collection of Bereket Haileab. Sample 144b. Housed at Carleton College in Minnesota.
Type
Thin section
Relation
Collection
Citation
Bereket Haileab, “BH250-144b,” BH250 Mineralogy Teaching Collection, accessed April 25, 2026, https://bereket-haileab.geology.sites.carleton.edu/items/show/173.