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"Blood jasper"

Material name: Blutjaspis
Synonyms: "Bohnerzjaspis" (bean-ore jasper); Hornstein; Type 152
Material (geologic): Secondary coloured eluvial Upper Jurassic chert

Detail of multicoloured material
Foto: Matthias Rummer, 2001

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General characteristics

(In part adapted from Unser 1977 and Zimmermann 1995

Geographical setting: Both sites under discussion here lie in the westernmost part of the Black Forest in the Southern part of the Markgräfler Land, 15 kilometres North of Basel and 35 km Southwest of Freiburg/Breisgau in Southwest Germany. The geological situation here will have been quite similar to that of the famous Neolithic flint mine at Kleinkems, just 7 kilometres to the Southwest. Upper Jurassic sediments have been wedged between the mass of the Black Forest and the subsiding Rhine rift. Most limestones have been weathered during the Tertiary, leaving the chert nodules embedded in it as eluvial material in the resulting loamy soil.
Material and colour: Impression of variability
  Geologically, the material found in the area is a Upper Jurassic, most likely Oxfordian chert, very similar to the material found in Kleinkems. After the erosion of the mother rock (limestone), probably predominantly during the Tertiary, in the resulting residual loam large amounts of iron were mobilized. These salts precipitated as small concretions with a very high iron content, locally known as "Bohnerz" (Bean-ore). This type of ore was mined in all of Southern Germany on quite a large scale since later prehistoric times, right up to the 19th century, resulting in large tracts of, mostly undatable, extraction sites indicated on topographical maps as "Schürfgrubenfeld". The same iron salts infiltrated the washed out chert in the loam, giving it a mostly reddish, brownish or yellowish colour. These siliceous materials are known in the German literature as "Bohnerzjaspis" (Bean-ore Jasper), because of their association with aforementioned ores.

The material found in a smallish region around the villages of Liel and Schliengen also belongs to the general group of these wrongly named "jaspers", but because of a high incidence of red hues, it is known as "Blutjaspis" (Blood Jasper). As you can see in the composite photo above, the material is highly variable, and very attractive. The picture is not to scale, and consist of a selection of photos just cut together to give an impression of its range of variation.
Although highly variable, the most typical colours of the "jasper" are 5R 4/6 to 7.5R 5/6 (red) and 10YR 6/6-6/8 (yellow) with 7.5R-10R 6/6 (light red) and 2.5Y 7/4-7/6 (pale yellow to yellow) as well as 2.5YR-10YR 8/1 (white) not uncommon. Quite a lot of our sample consists of hardly discoloured material (virtually) undistinguishable from the fresh material from Kleinkems. If there is a difference, it lies more with the bands being less pronounced than with a difference in basic colouring, although the lighter hues seem predominant. The one piece of knappable material we found at Hertingen is basically light yellowish brown to pale yellow (2.5Y 7/3 to 6/3) with a grayish brown band (2.5Y 5/2) and white to pale yellow patches (2.5Y 8/1 to 8/3).
The cortex is practically absent as all material with a higher carbonate content has been dissolved. Some nodules show clear signs of being rolled by water. Apart from (slight) banding and the same kind of inclusions described for Kleinkems-Isteiner Klotz, no special internal features can be made out. All of the more strongly coloured material is completely opaque.
The most typical material, as far as we have seen any descriptions and photos of this raw material, seems to be the yellow variety with a red core.

Other information: Although the sites at Schliengen as well as Hertingen were given a official prehistoric mine number (Weisgerber et al. (eds.) 1999) deplorable little information has been published on the sites as well as on the material. What we have seen at Hertingen and Liel, was certainly a mining area, but very probably a (historic?) extraction field for the Bohnertz iron ore.
The situation in Schliengen/Liel and immediate surrounding is little better. Two archaeological test trenches have been dug in 1976 in the area were we took our sample (Unser 1977). Unfortunately, here only traces of sub-recent mining (probably 19th century), for either the iron ore or the jasper, could be uncovered. As the Blutjaspis has been popular as a gemstone in the region for quite some time, it is to be expected that most prehistoric extraction sites, if there were any, will have been obliterated by more recent diggings. Although not proven, and as already said it might be unprovable, prehistoric mining is probable. There are large amounts of knapping waste lying around (although again of very unsure date), the material is very attractive, well-knappable and would have been easily explored due to its residual position in easily excavated loam.
Knapping notes: Most of the typical red and yellow material we found during our visit of the sites is to small to do serious experimental knapping, but the fractures seem quite smooth and conchoidal. The only large nodules we picked up were very similar to the material from Kleinkems but due to internal fracturing caused by weathering, it is a far cry from the fresh material. In all it can be said that it is a medium to reasonable quality material, but its attractiveness lies certainly more in its colourful appearance than in its knappability.
Archaeological description: Like for the mining, publications about the prehistoric use and distribution of the material are very scant. The area between Schliengen and Liel is thought to contain large Palaeolithic knapping floors, but the evidence for this is very poor. The dating is based on some large artifacts and "Clactonian" flakes, and as usual on the absence of pottery. Looking at the illustrations in Unser 1977, we are quite unconvinced that all those flakes and (pseudo-)tools are of a Lower Paleolithic date. To us it looks a lot like the general waste to be found an any extraction or mining site were the preliminary testing and working of the flint took place on the spot. If there is prehistoric mining and knapping going on, it is much more likely to date to the Neolithic, although parallels with the proven Mousterian site of Fontmaure in France, were a similar brightly coloured material occurs, are striking, but convincing bifacially worked handaxes from Schliengen are still lacking.
For information on the distribution of the Blood Jasper we only can rely on information concerning the Neolithic as published by Zimmermann (1995). He mentions just a few sites were this material has been found, with the northernmost occurrence South of Frankfurt/Main, some 250 kilometres to the North. In the region of the Southern Black Forest and surrounding areas the material seems to be quite common from the Upper Palaeolithic to the Neolithic, but again very little seems to have been published.
We expect the Blutjaspis to be mostly of local to regional importance, with a very sharp fall-off after 50-100 kilometres, but single pieces of the material might well turn up at considerable distances from the source, probably handed down as curiosities, especially in Middle Neolithic contexts in Western and Central Germany, Northern Switzerland and Eastern France.
As the material is often indistinguishable from other Bohnerzjaspis, and should be genetically lumped with this type of material, it will probably never become clear how and whereto the material was distributed in prehistory.

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Locality: Schliengen, Hohlenbachtal, Lörrach district, Baden-Württemberg, Germany
Synonyms: Schliengen-Liel; Mining-site D 30, according to the catalogue of the museum in Bochum (Weisgerber et al. (eds.) 1999; FlintSource sample 112.
Geographical description: The site where we did do our sampling lies quite exactly half-way between Schliengen and Liel, in a small valley called "Hohlenbachtal". The region is quite hilly with the highest points reaching altitudes of well over 500 metres, with narrow valleys in between. We followed the coordinates given for the extraction site as given in Zimmermann 1995, but according to the map in Unser 1977 (reproduced in Gayck 2000), there are quite a lot of other sites in a triangle between Bad Bellingen, Kandern and Auggen where the material can be found.
Geographical co-ordinates: Lat. 47° 44' 48" N
Long. 007° 35' 34" E
(Mapdatum WGS 84)
Co-ordinate precision: As we didn't take a note where the coordinates were taken with our handheld GPS, we can't exactly tell you how reliable they are, but the will be good enough to get you to a spot very near the place were the photo of the site was take below.
Other topographical information: As you can see in the site-picture, a road runs directly through the sampling area. This is road L 134 connecting Schliengen with Liel and Kandern. The easiest way to reach the site is from the west, where you leave the A 5 motorway at exit 65 "Müllheim/Neuenburg". From there follow the B 378 to the East until you reach the B 3, just West of Müllheim. Turn to the South on the B 3, the access is just after the viaduct to the right, and follow this road past Auggen to Schliengen. Here you have to take a left turn after the church, signposted Kandern. Follow this road for a bit more than a kilometre until you see the small rise as shown in the photo below at your left hand. You are now in the middle of the core region were the Blood Jasper occurs. If you are looking for a readily available topographical map to facilitate the navigation in the area, get the 1:50 000 "Freitzeitkarte 508 Lörrach-Belchen (Naturpark Südschwarzwald Blatt 3)", which you can use for visits to Kleinkems and Dinkelberg too.
Additional information: Sampling location between Schliengen and Liel
Foto: Rengert Elburg, 2000
  In the picture above you are looking across the road from Schliengen to Liel to the Northeast. As you can see, the visibility in the area is quite bad, and you have to look hard for any exposures or ploughed fields.
Visitors information: There are quite a lot of good eating- sleeping- and drinking-possibilities around, but we didn't explore them as we preferred to work out of Freiburg, just over 30 kilometres to the Northeast. More information about the infrastructure in the region can be found under the visitors information section on Kleinkems.
Sampling information: As we only followed the pin-point coordinates for the presumed mining site and didn't have the map in the publication of Unser at hand, we sampled only a very limited area around the coordinates given above. As hardly any subsoil was exposed, we only found a very limited amount of material. according to the literature, literally tons of the stuff have been found as the road between Schliengen and Liel was reconstructed. But as the material is so attractive and quite popular as a gemstone with (not only) local collectors, most pieces that come to the surface are picked up quite quickly, leaving the area badly depleted of good specimens.
This popularity with amateurs and other collectors explains why quite a lot of the farmers in the area react not too friendly if you ask them if it is possible to walk their fields.
  Intensely coloured piece of chert
Foto: Matthias Rummer, 2001
Intensely coloured piece of chert.
Length 33 mm
Yellowish nodule with cortex
Foto: Matthias Rummer, 2001
Yellowish nodule with cortex.
Width 65 mm
  Slightly atypical flake of "Blutjaspis"
Foto: Matthias Rummer, 2001
Slightly atypical flake of "Blutjaspis".
Width 28 mm
White flake with slight colouration
Foto: Matthias Rummer, 2001
White flake with slight coloration.
Length 60 mm
Sample description: The most typical piece in our collection is the one shown below. It shows part of a small nodule of yellow chert with an indistinct core of red. The piece at the left in the top row is a good example of how the infiltration of the different colours takes place with yellow material under the cortex and near a fracture and bright red material in the deeper places. Next to it is a split small nodule with hardly any discolouration in the banded material directly under the cortex and a yellow core, probably in the much more homogenous material.
The red flake with white spots in the bottom row is more of a curiosity. It seems to be not very typical (it's the only piece of the type we found), but as it looks very good we include it in this page. The lighter flake at the right is included to show how much this material can look like the chert from nearby Kleinkems. Although the bands have become less pronounced and there has been some reddish discolouration in the core, it is clear that the two materials are very close in their origin.
  Piece with typical red core
Foto: Matthias Rummer, 2001
Piece of typical "Blutjaspis" with red core
size 44 mm

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Locality: Hurrberg near Auggen, Lörrach district, Baden-Württemberg, Germany
Synonyms: Source E 5, according to Affolter 2002
Geographical description: The one sample described on this pages comes from the western side of the Hurrberg, just to the south of Auggen. The neares toponym on the 1:25 000 map of the area (number 8211) is a small valley called Maucherboden. As it seems to be a stray piece without any geological context, the site isn't of any serious importance (seen 'sampling information' below)
Geographical co-ordinates: Lat. 47° 46' 33" N
Long. 007° 35' 37" E
(Mapdatum WGS 84)

In cooperation with our technical partner I/O-graph, we offer a transformation-service for the coordinates of the sampled sites. Just click here to send a mail.

Co-ordinate precision: The coordinates were taken with a handheld GPS-receiver at the exact spot where the stone was found.
Other topographical information: The area can be reached by a narrow road which services the large tracts of vines which are grown here for the local white wine. As it is a popular area for hiking, the road also serves a footpath, and is marked. Trying to find your way out of Auggen to the south is a bit of a problem though, and we advise to bring a good topographical map.
Additional information: View on the village of Auggen
Foto: Rengert Elburg, 2003
  In the photo above, you are looking at the village of Auggen from the northern side of the Hurrberg. In the background the vines used to make the local white whine, Auggener Schäf, can be seen.
Visitors information: We visited the area on a small excursion to the region in 2003, as we were in the area to visit the excavations in the Neolithic flint mine of Kleinkems. During this stay, we camped in nearby Steinenstadt, some 4 kilometres southwest of Auggen. A word of warning about camping in Steinenstadt: there are two camping-grounds in/near this village, we stayed at the one directly in the village, the other one, a kilometre to the south near a former gravel-pit, seems to be a nudists' place. In Steinenstadt, there are a few places where you can eat and drink, so you can leave your transport at the camping and sample some of the local wines without endangering yourself and the traffic.
Sampling information: Normally, we wouldn't publish just the one stone, but as Auggen is a reputed source for the Blood-Jasper we use the opportunity to review this source. According to Affolter 2002, Auggen is the main source of type 152-chert, which corresponds to the material described on this page as "Blutjaspis". As the coordinates for this source seem to be quite approximate, we had a look at the map in Unser 1977 to get a more precise localisation. In the latter publication the whole area to the south of Auggen is marked as a geological source of the material. Unfortunately, we didn't have the detailed geological map of the region in our library then, so we took all information on face-value. We surveyed the whole area around the Hurrberg, but didn't find anything but this one piece.
After this, we obtained a copy of said geological map 1:25 000 (number 8211 "Kandern"), which showed the area were we searched for the material to be mainly covered in Loess and other Quaternary deposits, with some smallish areas of Tertiary sediments coming through. Blood-Jasper, however, is closely associated with the so called "Bean-ores", like outlined above, of which there are indeed some very localized patches in the surroundings of Auggen (unit "BO" on the local geological map), but certainly not on the ridge of the Hurrberg.
But even those small patches of "Bohnerz"-sediments in the area do contain very little siliceous material indeed. During a later visit to the region, we checked several of them, mostly directly to the south and northeast of Auggen, but didn't find a single piece of serviceable chert. Probably most material rests in the collections of local rockhounds.
Foto: Matthias Rummer, 2004
Stray piece of "Blood Jasper" from Auggen
size: 46 mm
Foto: Matthias Rummer, 2004
Dorsal view of the same specimen
size: 46 mm
Sample description: After all, it is worthwhile to have a closer look at the hi-res photo of the piece, as several characteristics of the material are clearly illustrated. Firstly, there is the typical colouring with a core in reddish hues, with a, in this case very narrow band, of yellow material under the surface. Both colours are due to impregnation with iron-salts, but under different oxidizing/reducing environments. This effect can be best seen in a piece from Schliengen towards the top of this page, where the yellow colour follows an internal fissure, as well as in some pieces from Liel.
A further interesting detail is the stong banding in this specimen, with apparently also some differences in the form of which the iron-ions (Fe2+/Fe3+) are present, possibly related to the content of organic matter in the chert. Especially noteworthy are the contrasting fossils, that stand out clearly due to their lack of pigmentation, an effect also seen in the Liel-chert, bur not as pronounced, due to the lesser degree of impregnation.


Last modified on:
January 29, 2006
Contents primarily by:
Rengert Elburg
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