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Amber through the eyes of a Geologist

The gemmological notion of precious and decorative stones also includes amber, which is a mineral regardless of its organic origin.

The digenetic processes, climate and environmental humidity changes, which the resin of both coniferous and broadleaf trees had undergone for millions of years, caused amber—in the broad sense of the term—to become an especially beautiful, warm and well-liked gemstone.

Due to its origin, as the resin of one of the Pseudolarix species—the Pseudolarix wehri— it was named succinite by Breithaupt. With its Eocene deposits found in Poland on the Leba Elevation and in Russia’s Yantarny mine in the Sambia Peninsula, succinite is known as Baltic amber.

The 15 m-thick deposit in Poland near Chlapowo, test-drilled three times, holds promise of significant resources. Unfortunately, it is located approximately 130 m below the surface, which is too deep to make open-cast mining possible. Small-time amber prospectors use only the amber accumulations in the Baltic fossil beaches or, for example, in Poland’s Kurpie Region outwash plain (sandur) formed in the Pleistocene by the rivers flowing from under the glacier during its stagnation. Amber can also be found in so-called rock floes transported by the continental glaciers that caught on the outcrops of the Eocene blue earth in Sambia.


Amber in Germany, known as Saxon amber, is somewhat younger than the Eocene- Oligocene. Mined until 1990, the Saxon amber deposit was then flooded to reduce dust pollution. Currently, mining is being re-launched at the Bitterfeld deposit from a floating platform.

The deposit, which was successfully operated for 16 years at Goitsche Mine and surrounding areas, can be referred to as a natural amber laboratory. The region near Halle is also an area with a great abundance of accessory resins that accompany succinite deposits. Gedanite, beckerite, stantienite, glessite and goitschite—with many varieties—and siegburgite are found in the layers between brown coal beds.

In Ukraine, in Sarny and Klesiv, amber is known as Ukrainian amber. Like Baltic and Saxon amber, it is classified as succinite based on IR spectra, but its yellow colour is different (cold). Moreover, amber from the deposit that partially rests on basalt is worn smooth to a large degree, especially in larger pieces. It also has a dark-brown weathered surface. Where the amber had no contact with basalt, it is similar to Baltic amber. In other words, it is not weathered, and its natural forms are mostly preserved.

In a much wider sense, the term “amber” is also used to describe the resins of many other trees that have not yet received their proper names such as gedanite, glessite, cedarite, simetite or valchovite. Dominican amber or Indonesian amber is one such example.

As indicated by archaeological excavation in northern Poland, amber was known in the Zulawy Lowlands very early on, with Neolithic ornaments preserved in unexpectedly large numbers in very good condition. Research on amber itself was initiated only by Gdansk-based pharmacists, and we should mention the work by people such as Otto Helm and P. Dahms in the late 19th and early 20th centuries.

The collections at the Museum of the Earth in Warsaw, along with the geological research on the Eocene sediments that amber deposits are associated with, have been identified with several boreholes from Chlapowo to Karwia and the Hel Peninsula. We also know that amber was scattered in the Quaternary by the glaciers and the rivers flowing from underneath them. This made it possible to locate the Kurpie sandur, rich in amber, and the accumulations in the Brda River basin in Poland’s Kashubia Region.

Fishing for amber in the Baltic sea
Fishing for amber in the Baltic sea
Mining for amber on the Holocene deposits in Gdansk
Mining for amber on the Holocene deposits in Gdansk

Wider-scale research on amber as such began to develop only in the second half of the 20th century. It began with research on organic inclusions, namely arthropods (especially from the family Ceratopogonidae) and fragments of plants in amber. The number of holotypes of arthropods designated at the time and published in 2001 by Polish and international palaeontologists grew much slower in later years. The latest research on Indonesian fossil resins enabled a discovery that profuse resin production was caused by volcanic activity.

The jewellery industry has the biggest interest in amber. Media reports indicate that the value of the Polish jewellery market grows by 13 per cent per year on average. Annually, Poland processes 200 tonnes of raw amber, and Polish amber products are known all over Europe and in many parts of the world. We remember the huge demand from China, which has clearly shaken up the prices for the products from Polish arts and crafts masters.

Amber was crafted in Poland by the people of the Kurpie and Kashubia regions, whose artefacts from the 18th century can be found in museums. One may venture to say that the development of folk art bridged the time gap between the period when only souvenirs were produced and today’s more diverse designs.


This article was first published in Summer 2018 edition of InColor magazine: incolormagazine.com. Reprinted with permission from International Colored Gemstones Association: gemstone.org. Images courtesy of the International Amber Association.











ABOUT THE AUTHOR
Barbara Kosmowska-Ceranowicz

Professor Barbara Kosmowska-Ceranowicz, Ph.D., is a geologist, an amber expert at the International Amber Association and a prominent researcher of amber. Since 1956, she has worked at the Museum of the Earth, Polish Academy of Sciences. From 1974 to 2007 and from 2008 to 2010, she served as Head of Amber.









Friday, 14 December, 2018 10:36am
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