place: Java, Indonesia
coordinates: 6°36’S 110°44’E
classification: Pallasit, PMG
total weight: 499,5 kg
Meteorites are rarer than gold on the earth’s surface and only very few of them are Pallasites – a unique structure of metal and gemstone. They come from the asteroid belt between Mars and Jupiter and the material is 4,60 billion years old and are the part of the transition zone between the mantle and the core of an asteroid. The first one was discovered in 1749 at Krasnojarsk/Russia and described by Peter Simon Pallas, a German scientist. Consequently, the meteorite group was named Pallasites in honour of him. Over the last centuries only 36 pieces of the Main Group have been found, half of them are less than 20 kg. With reference to his weight Jepara is the five largest Main Group Pallasite.
The meteorite was discovered in May 2008 during excavation activities at Jepara/Indonesia. A new hall for producing furniture had been under construction and Jepara has been dug out while building the foundation of this premises.
The mass of the meteorite was 499,50 kg in an almost spherical shape with a shortest and longest diameter of 70 cm and 85 cm. The crust of approximately 2 – 4 cm is weathered and rusty.
Jepara shows a homogeneous distribution of coarse-grained rounded Olivines from approximately 6 -12 mm size (64 %). The groundmass is composed of secondary Magnetite (23 %), Nickel Sulfide and Sulfate (8%) and Schreibersite (5%). All the different elements are very finely spread , which gives Jepara a unique look, really different from other Pallasites. The Olivines are very clear and mostly without cracks.
Olivines are homogeneous in composition (FA12-13). Sulfides is composed of NiS and may represent a replacement product of Troilite, while Magnetite(Fe3O4) is a weathering product of primary FeNi phases. Schreibersite has the composition (Fe1.85Ni1.15). This shows that Jepara has been on our planet for quite a long time before he was found.
The main analyses was done at University of Bayreuth/Germany and the isotope analyses are made by the University of Göttingen/Germany.