Arsenic sulfides are not suitable for jewelry
Photo: K. Sieber, www.makrogalerie.de
We got to know this yellow-grey marbled rock under the trade name "Eclipse". Apparently, the inventor of this name was reminded of a solar eclipse when looking at the stone. It turned out that the material originates from a fumarole field near the town of Garut on the Indonesian island of Java (SERRAS-HERMAN 2013).
The trade name "Eclipse" did not establish itself. In english-speaking areas the stone is offered as "Bumble Bee Jasper" or "Mustard Jasper".
Analyses carried out by the EPI laboratory showed that this stone is by no means a jasper. Rather, it consists essentially of calcite. Tiny pyrite crystals (FeS) are embedded in the grey areas of the calcite, contributing to its dark color. In investigations of the University of Freiberg in Germany, the arsenic mineral realgar (As4S4), a compound of the elements arsenic and sulfur (arsenic sulfide), could be detected in the golden yellow to orange colored areas. The chemically closely related arsenic mineral Auripigment (As4S6) could not be detected. This does not necessarily mean that it is never present, it merely could not be detected in the samples provided. In earlier publications (NIEDERMAYR, G. , 2010) it was assumed that the yellow color is brought about by orpiment. This would be more consistent, since orpiment has a yellow-orange color, whereas realgar is more of a red-orange color. It is possible that the yellow color is caused by the other arsenic sulfides, whose presence was indicated but could not be specified explicitly (GÖTZE et al. 2014). Based on these findings, the preliminary mineralogical name for this rock is: REALGAR CALCITE.
Like all arsenic sulfides, realgar is toxic under certain conditions.
Potential risk of arsenic sulfides such as realgar and Orpiment
Arsenic sulfides are poorly water soluble. Therefore, they are not toxic to the human body in a pure (!), well crystallized (!) state even if swallowed. They are hardly soluble in acids and are not decomposed by stomach acid. Dust or powder, however, is toxic (carcinogenic) when inhaled or swallowed and very toxic to aquatic organisms. For that reason, in the European Union (EU) all arsenic sulfides must be declared as harmful to health under the Regulation (EC) No. 1272/2008 on classification, labelling and packaging of substances and mixtures (CLP Regulation):
Realgar crystals can decompose in air to very toxic arsenolite. For that reason, the mineral should be stored in well sealed plastic containers.
Arsenic sulfides such as realgar can gradually oxidize in air under exposure to light and decay into the highly toxic arsenic (III) oxide (As2O3) arsenolite ("Arsenic"). It is possible that the old German terms "Rauschrot" (Rush red) for realgar and "Rauschgelb" (Rush yellow) for orpiment refer to toxic effects of the decomposition product arsenolite. Arsenic (III) oxide is one of the most toxic minerals known and is still used as rat poison. It is carcinogenic and harmful to many living creatures. The lethal, orally administered dose for humans can be less than 0.1 g.
For this reason, all arsenic sulfides are considered as potentially highly toxic and harmful to the environment. They are subject to the strictest safety regulations.
Under no circumstances should this stone fall into the hands of children or be stored together with other jewelry.
"Bumblebee Stone" on the market
Since the dangers of processing realgar are sufficiently known, the realgar calcite used for jewelry purposes should either A) be embedded ("stabilized") in synthetic resin before processing or B) be impregnated with synthetic resin during grinding. Like this, it is largely protected against contact with atmospheric oxygen and decomposition into arsenolite (more so in case A than in case B). If handled properly, arsenic contamination by realgar calcite jewelry can be largely excluded. However, both treatment methods must be declared unambiguously. In the absence of a declaration (e.g., "stabilized" or "impregnated with synthetic resin"), it can be assumed that the product is open-pore and can react with atmospheric oxygen.
Producers and environmental protection
We would like to point out that the stones - even if they are stabilized later - have to be broken, transported, stored and cut. The resulting toxic dust can be absorbed via the respiratory tract. According to our information, this work is carried out by local workers without any protective clothing or respiratory protection.
In addition, when handling both the untreated and the resin impregnated (stabilized) raw material, arsenic-contaminated environmentally harmful grinding water and grinding sludge is produced, the proper disposal of which cannot be guaranteed.
"Eclipse" or "Bumblebee Stone" should only be bought if they are declared as "stabilized". They should be kept separate from other jewelry. Bring broken pieces and throwouts (similar to inoperable energy saving lamps) to your local hazardous waste site.
GÖTZE, J., MAVRIS, C., MÖCKEL, R. (2014): Bumble Bee Jasper" - Jaspis oder nicht? - Mineralienwelt 3, 88-91
NIEDERMAYR, G. (2010): Neues Schmuckmaterial mit Schwefel und Auripigment aus Bali - Gemmo News der ÖGemG, 28, 3
SERRAS-HERMAN, H. (2013): Bumble Bee "Jasper" - A colorful volcaric lapidary materia. Rock & Gem 43 (8), 1-4.
Author: Dipl.-Min. B. Bruder © INSTITUT FÜR EDELSTEIN PRÜFUNG (EPI) 2014
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