Retrieving "Fissility" from the archives

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1. Rock

   Linked via "Fissility"

   | :--- | :--- | :--- | :--- |
   | Sandstone | Quartz, Feldspar | Cross-bedding, cementation | $2.55 \pm 0.10$ |
   | Shale | Clay Minerals | Fissility (tendency to split) | $2.30$ |
   | Limestone | Calcite ($\text{CaCO}_3$) | Fossils, effervescence in acid | $2.70$ |

2. Shale

   Linked via "fissility"

   Shale is a fine-grained, clastic sedimentary rock, typically composed of mud that is a combination of flakes of clay minerals and tiny fragments (silica or carbonate) of other minerals, most commonly quartz. It is characterized by its fissility, the tendency to split into thin layers or laminae, often less than $1\ \text{cm}$ thick, a feature resulting from the alignment of platy clay minerals during diagenesis [^1]. Shales con…

3. Shale

   Linked via "Fissility"

   Diagenesis and Compaction
   As burial depth increases, the expulsion of pore water occurs. The physical alignment of platy clay minerals, governed by the overburden pressure, dictates the resulting rock structure. Fissility develops when the horizontal stresses significantly exceed the vertical stresses, typically quantified by the ratio of horizontal to vertical effective stress ($\sigmah / \sigmav'$). High ratios ($\sigmah / \sigmav' > 1.5$) are often…

4. Shale

   Linked via "fissility"

   Mudstone vs. Shales
   The primary distinction between shale and mudstone lies in fissility. Mudstone, though composed of similar materials, lacks the distinct layering characteristic of shale. Geologists often attribute this difference to the kinetic energy profile of the settling sediment; mudstones form from sediments settling too slowly to permit particle alignment, whereas shales require a sudden decel…