BH250-43
Title
BH250-43
Subject
Marble
Description
BH250-43 is a marble, a metamorphic rock formed primarily by the recrystallization of carbonate minerals, typically derived from limestone or dolostone protoliths. Marble is well-known for its relatively uniform texture and ability to take a polish, which makes it widely used in sculpture and architecture.
The major minerals in marble include calcite (CaCO₃), which is the dominant mineral in most marbles derived from limestone, and dolomite (CaMg(CO₃)₂), which predominates in marbles formed from dolostone protoliths. Minor accessory minerals present can include quartz, muscovite, or biotite mica.
The protolith of marble consists of carbonate sedimentary rocks such as limestone or dolostone, which undergo metamorphism to form the recrystallized texture characteristic of marble.
The carbonate minerals in BH250-43 exhibit twinning lamellae, important microstructural features in marble. Calcite commonly shows mechanical and growth twinning, appearing as planar, microscopic parallel bands or lamellae within the crystal lattice. These twinning lamellae develop in response to differential stress or strain during regional metamorphism, representing deformation-induced lattice reorientation that accommodates strain without fracturing. The density and orientation of twinning lamellae provide valuable information about the rock’s deformation history and the stress conditions it experienced during metamorphism.
By analyzing factors such as the location of relief changes to identify the c-axis, the Miller indices of the twin lamellae, the angle the twin lamellae make with the c-axis, and whether this angle is acute or obtuse, geologists can distinguish whether the carbonate mineral is calcite or dolomite.
The major minerals in marble include calcite (CaCO₃), which is the dominant mineral in most marbles derived from limestone, and dolomite (CaMg(CO₃)₂), which predominates in marbles formed from dolostone protoliths. Minor accessory minerals present can include quartz, muscovite, or biotite mica.
The protolith of marble consists of carbonate sedimentary rocks such as limestone or dolostone, which undergo metamorphism to form the recrystallized texture characteristic of marble.
The carbonate minerals in BH250-43 exhibit twinning lamellae, important microstructural features in marble. Calcite commonly shows mechanical and growth twinning, appearing as planar, microscopic parallel bands or lamellae within the crystal lattice. These twinning lamellae develop in response to differential stress or strain during regional metamorphism, representing deformation-induced lattice reorientation that accommodates strain without fracturing. The density and orientation of twinning lamellae provide valuable information about the rock’s deformation history and the stress conditions it experienced during metamorphism.
By analyzing factors such as the location of relief changes to identify the c-axis, the Miller indices of the twin lamellae, the angle the twin lamellae make with the c-axis, and whether this angle is acute or obtuse, geologists can distinguish whether the carbonate mineral is calcite or dolomite.
Creator
Bereket Haileab
Source
From the rock collection of Bereket Haileab. Sample BH250-43. Housed at Carleton College in Minnesota.
Type
Thin section
Relation
Collection
Citation
Bereket Haileab, “BH250-43,” BH250 Mineralogy Teaching Collection, accessed April 25, 2026, https://bereket-haileab.geology.sites.carleton.edu/items/show/48.