As can be seen from Tables 1 and 6 and Figure 2, the Staric sandstone is characterised by a relatively high degree of rock compaction (diagenesis), of which the concavo-convex to sutured grain contacts, authigenic
silica overgrowths onto the detrital quartz grains or even intensive silicification of clay matrix are the microscopic indicators.
clays in sandstones: recognition and influence on reservoir properties and paleoenvironmental analysis.
chlorite occurred in the Chang 7 sandstone as two forms: grain rims and pore-filling.
Mineralogy, geochemistry and cathodoluminescence of authigenic
quartz from different sedimentary rocks.
Biodiversity on the rocks: Macrofauna inhabting authigenic
carbonate at Costa Rica methane seeps.
There are massive authigenic
quartz crystals spreading between the particles.
In a number of cases, these authigenic
clays were found in fairly young craters, ones formed in the last 2 billion years or so.
Jordan samples from Arcadia, in Trempealeau County, Wisconsin, show originally rounded quartz grains with second-stage rounding of quartz overgrowths indicative of multi-cycling, and authigenic
feldspar overgrowths that result in localized compromises to optimal frac sand properties (Runkel and Steenberg, 2012).
The above-mentioned eight chemical elements are related to organic, carbonate or other authigenic
components of lacustrine sediments.
2005) and can be formed by either authigenic
or diagenetic processes related to a chemical, physical, or biological change after its initial deposition.
If not fully removed, elements can precipitate as or become incorporated in authigenic
minerals such as jarosite (K[Fe.sup.3+.sub.3][(S[O.sub.4]).sub.2][(OH).sub.6]) or Fe-oxyhydroxides.
These processes mainly reflect interaction of the basaltic glass clasts and glass rich matrix with the percolating water, including palagonitization, formation of authigenic
clays, zeolites and calcite (Kabesh et al., in press).