BH250-44
Title
BH250-44
Subject
Marble Containing Wollastonite
Description
Major Minerals: wollastonite, dolomite
Minor Minerals: quartz, zircon
Mineralogy Comments: contains calcite/dolomite cut perpendicular to C-axis
BH250-44 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, making it widely used in sculpture and architecture.
The major minerals in BH250-44 include dolomite CaMg(CO₃)₂, which predominates in marbles formed from dolostone protoliths, and wollastonite, a calcium silicate mineral that can form during metamorphism of impure carbonate rocks.
The protolith of marble consists of carbonate sedimentary rocks such as limestone or dolostone, which undergo metamorphism to develop the recrystallized texture characteristic of marble. Based on the mineral assemblage of BH250-44, its protolith must have contained some siliceous material. The presence of wollastonite indicates that silica was available to react with calcite during metamorphism. This reaction can be represented as:
CaCO3 + SiO2 ⟶ CaSiO3 + CO2
One of the thin sections of BH250-44 has a sphene (titanite) with zircon inclusion showing pleochroic halo (radiation damage). See the photomicrograph.
Minor Minerals: quartz, zircon
Mineralogy Comments: contains calcite/dolomite cut perpendicular to C-axis
BH250-44 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, making it widely used in sculpture and architecture.
The major minerals in BH250-44 include dolomite CaMg(CO₃)₂, which predominates in marbles formed from dolostone protoliths, and wollastonite, a calcium silicate mineral that can form during metamorphism of impure carbonate rocks.
The protolith of marble consists of carbonate sedimentary rocks such as limestone or dolostone, which undergo metamorphism to develop the recrystallized texture characteristic of marble. Based on the mineral assemblage of BH250-44, its protolith must have contained some siliceous material. The presence of wollastonite indicates that silica was available to react with calcite during metamorphism. This reaction can be represented as:
CaCO3 + SiO2 ⟶ CaSiO3 + CO2
One of the thin sections of BH250-44 has a sphene (titanite) with zircon inclusion showing pleochroic halo (radiation damage). See the photomicrograph.
Creator
Bereket Haileab
Source
From the rock collection of Bereket Haileab. Sample BH250-44. Housed at Carleton College in Minnesota.
Type
Thin section
Relation
Collection
Citation
Bereket Haileab, “BH250-44,” BH250 Mineralogy Teaching Collection, accessed April 25, 2026, https://bereket-haileab.geology.sites.carleton.edu/items/show/49.