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The quarry at the Karrenberg mountain and the development area in Reichweiler (been because of the slope of the Karrenberg mountain) developed in the postwar years to a finding location for some of the most beautiful agates of Germany. The Karrenberg mountain and the nearby Weiselberg mountain at Oberkirchen are former volcanic chimneys of permian age.
The formation of the agates at the Karrenberg mountain is extremely complex and most interesting. This becomes recognizable on the one hand at the succession of the mineralisations within the agate-nodule range. Very often In the direct environment of the larger nodules one can constitute a small graphite inclusion, which is regarded developing carbon gases as jointly responsible for the cavitation of the nodule. These graphite inclusions were transported with the formation of the chimney, when this broke by more deeply lying coal-bearing carbonic layers. From the outside inward the large mineralisations: saddle-shaped carbonates and zeolites - chalcedony ( pseudomourphic formations of carbonates and zeolites) - fluorite yellow, hexaedric - hisingerite - zeolites (under other ferrierite-Mg) - chalkopyrite, sphalerithe, galena - chalcedony (as agate) - quartz (macro quartz as rock crystal, amethyst and rarely smoky quartz) - free crystallized ferric oxides (goethite and hematite) - violet fluorite and calcite inside the possibly remaining central cavities.
On the other hand the Karrenberg mountain seems to be the so far only discovery site for agates where the formation from directly neighbouring silicic acid existing in the rock as rock glass appears macroscopically visible. If one looks at the agate coating range in the host rock, one determines a more or less distinctive color change, which agitates ago from a devitrification of the rock. This crust is present with all agates. It will be well visible at cut specimen, those with surrounding host rock or at specimen, which are saved in situ in the strongly eroded range.
Further characteristics of the agates of the Karrenberg mountain let it appear structurally singular under the german agates:
Stacked spherulitical agate layers:
Beside usual agate-banding emerges here a special variant of spherulithical banding: Agate volumes, which more or less separated themselves in several, to a large extent parallel, partly wavily rejected levels by the nodule through. The following differences are present to the so-called “waterlevel-banding" (- which is occupied by only one specimen so far at the Karrenberg mountain) and to the common agate-banding:
1. The levels are not straight-lined gravitatively regulated. Inclined positions of levels and/or dents produce different thickness of spherulite formations.
2.At the structure of these volumes no fine-quartz is involved. Completely globular Chalcedony Spherulites without point of increasing (Holospherulithes) are not formed. Some levels are not complete (the germ formation was locally suppressed).
3. These agate layers often form interchanging crystallisations with macro-quartz .
4. The volumes did not result from upsetting, squeezing or distortion of the Chalcedony gelatin. There is no relationship between Querbaenderung and "Gallert valves" ( so called. "influence/discharge tubes”) . These layers are covering not the entire nodular range in spherical dimension, but represents genuine, although partial irregular levels, which divide the nodule in a cutting plane.
Similar formations do occur in Asni in Morocco .With these likewise very special agates the agates of Karrenberg mountain are having a further characteristic in common. Within the outside range of the nodule formation is a red pigmented chalcedony rim, which appears unstructured usually and very seldom is showing a multiplicity of curved and circle-similar designs. At the Karrenberg mountain as in Asni it comes also to the formation of super-spherulites (hemi-agates). These are expressed largely and pattern-dominating spherulites.
The agates of the Karrenberg mountain are expressed intensively colored. Beside the “red rim agates”already mentioned magenta-coloured agates are typical for the Karrenberg mountain. This colouring is usually only in larger agate nodules. Highly desired from collectors are also ink-blue to blue-violet colored agates. Zones of this colouring consist usually of homogeneous transluzidic Chalcedony without agate-banding. Yellow colours are very rare at the Karrenberg mountain.
Relatively rare at the Karrenberg mountain are agates with a strong “shadow-effect”.
A further characteristic of this find region are the so-called ”agate-lieser” - its own variant of vein agates, which were particularly found within the range of the development area Reichweiler into to approximately square meter-large plates. They show clear pseudomorphic structures in the outside range after a platy mineral (baryte?). If these plates are divided parallel to the vein direction they are showing a multiplicity of geometrically limited agates. A so far singular agate Lieser shows the education of individual, bubble-shaped agates in a mossy-like Chalcedony.
Under collectors highly desired are also the so-called “tube-agates”, which occurred mainly in the western part of the quarry. Often are the tubes sorrounded by orange Chalcedony and breaking through a deeply blue chalcedony. If a greenish layer of silicates is added, which around the tubes themselves, the agate shows a surprisingly multicolor picture.
more agates from this location are presented here.
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