Dolomite Textures
Dolomite (dolostone) is composed mainly of the mineral dolomite [CaMg(CO3)2]. [1] Unlike limestone, which is characterized by the presence of grains, micrite, and/or sparry cement, dolomite has a largely crystalline (granular) texture. [1]
Classification by Crystal Shape
On the basis of crystal shape, two kinds of dolomite are recognized. [1]
Planar (Idiotopic) Dolomite
Planar (or idiotopic) dolomite consists of rhombic, euhedral (well-formed) to anhedral (poorly formed) crystals. [1]
Nonplanar (Xenotopic) Dolomite
Nonplanar (or xenotopic) dolomite is made of nonplanar, commonly anhedral crystals. [1]
Subtypes
Each of these major kinds of dolomite can be divided into subtypes. [1]
Formation by Replacement
Many dolomites form by replacement of a precursor limestone. [1] Original limestone textures may be preserved in such dolomites to various degrees, ranging from virtually unreplaced to totally replaced. [1]
The replacing dolomite may preserve the original texture as a “ghost” (mimicking replacement) or the original texture may be completely destroyed (nonmimicking replacement). [1]
Related Topics
Crystal
The word crystal is used in two distinct ways in mineralogy, and the difference between them matters more than it might first appear.{/* SRC: Nesse p.5: "grains. It might be better to use the term...
Mineral
"Mineral" means different things depending on who you ask.{/* SRC: Nesse p.3: "Almost every human endeavor is influenced by minerals. Many natural resources used in the manufacture of" */}...
Micrite
Carbonate mud composed of very fine size calcite crystals is present in many ancient limestones in addition to sand-size carbonate grains.{/* SRC: Boggs p.140: "Carbonate mud composed of very fine...
References & Citations
- 1.Principles of Sedimentology and Stratigraphy Boggs
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