On October 3, 1815, around 10:00 am, a meteor went through the sky and a noise similar to a shooting was heard. A man, working in a vineyard in Chassigny, observed the phenomena and saw a rocky mass fall 400 m from him. The meteorite exploded on impact and the inhabitants of the village hastened to recover the fragments. Another witness claimed to have seen other stones thrown in the air in all directions. A second large piece was found a week later, 160 m from the first one.

The place where the phenomena occurred is located at a place called "Sous Prêle," halfway between Chassigny and the Bois de Moremaine. Fortunately, Mr. Pistollet, a doctor in Langres, who arrived two days after the fall, carried out a real field investigation, while collecting many fragments of the meteorite; this prevented this meteorite from being forgotten.

The total recorded mass of Chassigny is four kilograms. This is the total mass of all the fragments collected by Mr. Pistollet. There is no evidence that the pieces were weighed precisely. Mr Pistollet believed that about eight kilograms fell, based on the missing pieces of a one kilogram specimen he obtained. Of the 4 kg initially recovered, now less than a kilogram is preserved.  

From Wikipedia:

 "Chassigny is the meteorite for which the chassignites are named, and gives rise to the "C" in the name of the SNC group of meteorites. Chassigny is an olivine cumulate rock (dunite). It consists almost entirely of olivine with intercumulus pyroxene, feldspar, and oxides. It was the only known chassignite until NWA2737 was found in the Moroccan Sahara in northwest Africa.

Chassigny is particularly important because, unlike most SNCs, its noble gas composition differs from that in the current Martian atmosphere. These differences are presumably due to its cumulate (mantle-derived) nature."