There is not method miracle to release the fossils of their calcareous gangue. We will distinguish 2 techniques which we will use in a combined way.

Mechanical method : We will use initially small gravers worked starting from old high speed steel drills, whose end will be sharpened in the shape of gouge.

For the gravers of small size (2 - 3 mm) we always use points hard steel with the end sharpened in ' cuillère' and of which we cut the head in order to crimp it in a mild steel sleeve. Then it is necessary "to use" of the hammer with these small gravers on the gangue.

With a good blow of hand, in the tender cases of gangue and of an ammonite of the hoplites type, one manages to practically release all the fossil until the contact it cockles it except (or ' test') the last whorls in the umbilical point. There then remains a fine gray film which can be easily eliminated by brushing or with the chemical method that we will examine in a forthcoming page of the site....

The principal difficulty lies in the angle of attack of the graver and in the proportioning of the blow of hammer. Too much inclined, it slips on the gangue by tearing off weak glares, and by striping the shell of the fossil when one is very close; too much perpendicular, it is the accident with a cleavage which carries an end of shell with the gangue! This work is often complicated by the presence of cracks in the nodule. It is advisable to have a fast tube of adhesive with range of the hand, and a scheme of work often cleaned in order to find the glare of accidentally broken test easily.

To follow...... as of now....