BH250-175g
Title
BH250-175g
Subject
Tapeats Sandstone
Description
Major Minerals: quartz, feldspar
Sandstone is one of the most common sedimentary rocks and plays a critical role in sedimentary geology, stratigraphy, petroleum geology, and hydrogeology. It is a clastic sedimentary rock composed primarily of sand-sized particles (0.0625 to 2 mm in diameter), cemented together by a matrix of finer particles and/or chemical cement.
The most abundant mineral in sandstone is quartz, valued for its hardness and chemical stability. Feldspars—both plagioclase and K-feldspar—are also common, particularly in arkosic sandstones, although they are less chemically stable than quartz. Sandstones often contain lithic fragments, which are pieces of pre-existing igneous, metamorphic, or sedimentary rocks. Accessory minerals may include micas (muscovite and biotite), zircon, tourmaline, magnetite, and garnet.
The mineralogical composition of sandstone provides essential clues about its provenance. Provenance analysis is a powerful tool in reconstructing sediment transport pathways and inferring tectonic settings.
Cementation and Diagenesis:
Cementation is a diagenetic process whereby minerals precipitate in the pore spaces between grains, binding them together. Common types of cement include:
Silica (cryptocrystalline silica/quartz overgrowths)
Calcite (CaCO₃)
Iron oxides (e.g., hematite, goethite)
Clay minerals, such as Fe-rich illite (glauconite)
Sandstone Classification
Sandstones are classified based on grain composition and matrix content:
By Grain Composition (QFL: Quartz–Feldspar–Lithic Fragments):
Quartz arenite: >90% quartz
Arkose (feldspathic arenite): >25% feldspar
Litharenite: >25% lithic fragments
By Matrix Content:
Arenite: Clean sandstone with <15% matrix
Wacke: Mud-rich sandstone with >15% matrix (e.g., graywacke)
Depositional Environments
Sandstones form in a range of depositional environments, including:
Fluvial
Aeolian
Shoreline/Beach
Deltaic
Deep-marine (e.g., turbidites)
BH250 Sandstone Collection
The BH250 collection includes thirteen sandstone samples collected from southeastern Minnesota and from geology field trips across the Midwest, South Dakota, the Grand Canyon, and Death Valley. Each sample is accompanied by hand specimens, thin sections, and photomicrographs, providing an excellent foundation for detailed petrographic analysis. Here you will find short descriptions for each sandstone sample.
BH250-175g is sample collected from Grand Canyon which is the Tapeats Sandstone. The Tapeats Sandstone is the basal Cambrian sedimentary unit of the Tonto Group in the Grand Canyon and serves as a key marker for understanding the Cambrian Explosion and the Great Cambrian Transgression across North America.
It is a quartz-rich sandstone, ranging from arkosic to subarkosic compositions, with a conglomeratic base in some areas. The grain size is coarse at the base, often appearing as pebbly conglomerate, and gradually fines upward to medium or fine sandstone. Th cement in this sandstone is primarily silica or iron oxide.
The Tapeats Sandstone correlates with several Cambrian sandstones across North America, including the Mount Simon Sandstone of the Midwest (Illinois, Wisconsin, Minnesota).
Sandstone is one of the most common sedimentary rocks and plays a critical role in sedimentary geology, stratigraphy, petroleum geology, and hydrogeology. It is a clastic sedimentary rock composed primarily of sand-sized particles (0.0625 to 2 mm in diameter), cemented together by a matrix of finer particles and/or chemical cement.
The most abundant mineral in sandstone is quartz, valued for its hardness and chemical stability. Feldspars—both plagioclase and K-feldspar—are also common, particularly in arkosic sandstones, although they are less chemically stable than quartz. Sandstones often contain lithic fragments, which are pieces of pre-existing igneous, metamorphic, or sedimentary rocks. Accessory minerals may include micas (muscovite and biotite), zircon, tourmaline, magnetite, and garnet.
The mineralogical composition of sandstone provides essential clues about its provenance. Provenance analysis is a powerful tool in reconstructing sediment transport pathways and inferring tectonic settings.
Cementation and Diagenesis:
Cementation is a diagenetic process whereby minerals precipitate in the pore spaces between grains, binding them together. Common types of cement include:
Silica (cryptocrystalline silica/quartz overgrowths)
Calcite (CaCO₃)
Iron oxides (e.g., hematite, goethite)
Clay minerals, such as Fe-rich illite (glauconite)
Sandstone Classification
Sandstones are classified based on grain composition and matrix content:
By Grain Composition (QFL: Quartz–Feldspar–Lithic Fragments):
Quartz arenite: >90% quartz
Arkose (feldspathic arenite): >25% feldspar
Litharenite: >25% lithic fragments
By Matrix Content:
Arenite: Clean sandstone with <15% matrix
Wacke: Mud-rich sandstone with >15% matrix (e.g., graywacke)
Depositional Environments
Sandstones form in a range of depositional environments, including:
Fluvial
Aeolian
Shoreline/Beach
Deltaic
Deep-marine (e.g., turbidites)
BH250 Sandstone Collection
The BH250 collection includes thirteen sandstone samples collected from southeastern Minnesota and from geology field trips across the Midwest, South Dakota, the Grand Canyon, and Death Valley. Each sample is accompanied by hand specimens, thin sections, and photomicrographs, providing an excellent foundation for detailed petrographic analysis. Here you will find short descriptions for each sandstone sample.
BH250-175g is sample collected from Grand Canyon which is the Tapeats Sandstone. The Tapeats Sandstone is the basal Cambrian sedimentary unit of the Tonto Group in the Grand Canyon and serves as a key marker for understanding the Cambrian Explosion and the Great Cambrian Transgression across North America.
It is a quartz-rich sandstone, ranging from arkosic to subarkosic compositions, with a conglomeratic base in some areas. The grain size is coarse at the base, often appearing as pebbly conglomerate, and gradually fines upward to medium or fine sandstone. Th cement in this sandstone is primarily silica or iron oxide.
The Tapeats Sandstone correlates with several Cambrian sandstones across North America, including the Mount Simon Sandstone of the Midwest (Illinois, Wisconsin, Minnesota).
Coverage
Location: Mile 222 Campground, Grand Canyon, Arizona, USA
Nearby Geographic Feature: Grand Canyon
GPS Coordinates: 35.80535, -113.332917
Nearby Geographic Feature: Grand Canyon
GPS Coordinates: 35.80535, -113.332917
Date
August 2021
Creator
Bereket Haileab
Source
From the rock collection of Bereket Haileab. Sample BH250-175g. Housed at Carleton College in Minnesota.
Type
Thin section
Relation
Collection
Citation
Bereket Haileab, “BH250-175g,” BH250 Mineralogy Teaching Collection, accessed April 24, 2026, https://bereket-haileab.geology.sites.carleton.edu/items/show/234.