Fiber lime
| system | series | step | ≈ age ( mya ) |
|---|---|---|---|
| higher | higher | higher | younger |
| Paleogene | Oligocene | Chattium | 23.03 ⬍ 28.1 |
| Rupelium | 28.1 ⬍ 33.9 |
||
| Eocene | Priobonium | 33.9 ⬍ 38 |
|
| Bartonium | 38 ⬍ 41.3 |
||
| lutetium | 41.3 ⬍ 47.8 |
||
| Ypresium | 47.8 ⬍ 56 |
||
| Paleocene | Thanetium | 56 ⬍ 59.2 |
|
| Seelandium | 59.2 ⬍ 61.6 |
||
| Danium | 61.6 ⬍ 66 |
||
| deeper | deeper | deeper | older |
Fibrous lime is the name for a form of calcite ( calcium carbonate ), as it is found in the north German bed load , mainly in the east of Schleswig-Holstein and in the north of Mecklenburg-Western Pomerania .
It is fibrous limestone that grew up and down into the surrounding clayey layers from a tufa layer created by volcanic activity in the Eocene . The tufa layer therefore forms a kind of seam of the lime fibers, which from here mostly diverge at right angles to the growth surface, the cross-section of which is between 5 and more than 100 µm . The occasional explanation that the fibers grew together in a cavity and formed a seam at the place where they met, however, should not be true. The seam can still be seen on most of the finds. If it is missing, it is a piece that has broken apart at this point.
The pea-sized to fist-sized fiber limes, which are often found on the Baltic Sea beach and in gravel pits, are mostly yellowish-gray, sometimes also greenish in color. On the Mecklenburg Baltic Sea coast, pink fiber limes also occur due to the low manganese content , but they are rare. Fibrous limes sometimes have a nail head-like structure on their surface, parallel to the seam surface, and can easily be confused with fossil wood. Under the binoculars , however, fossil wood always shows a cell structure, whereas fibrous lime does not.
Calcite is a very soft material ( Mohs hardness 3) that can be easily processed. If you grind and polish fiber lime, this creates a velvety, shiny surface. Jewelery is therefore occasionally made from pieces of fiber lime that have not been weathered. The term “Baltic Sea Jade ”, which is sometimes used, can be traced back to this, whereby the fibrous lime has nothing to do with jade in the mineralogical sense. Other names are "Holsteiner Bernstein" and "Friesengold".
literature
- Kurt Hucke : Introduction to bed load research . - 132 p., 50 plates, numerous Text illus., Nederlandse Geologische Vereniging, Oldenzaal 1967.
- Werner Schulz: Geological guide for the north German bed load collector . - 507 p., Numerous Fig., Cw Verlagsgruppe Schwerin 2003. ISBN 3-933781-31-0 .
- Frank Rudolph & Marco Meyer: Fiber lime . - In: Der Geschiebesammler 45 (2): 47–60. Wankendorf 2012. online PDF