The Muséum’s collection of endogenous rocks is an inventory of the rocks formed inside the Earth. They are representative of magmatic plutonic or volcanic rocks, formed from the solidification of previously molten terrestrial materials (magma) and any type of rocks altered under the influence of temperatures and pressures prevailing inside the Earth (metamorphic rocks).


Due to the history of earth science collections at the National Museum of Natural History, a number of endogenous rock samples are still in the general geology collection.

Presentation/History
The endogenous rock collection contains around 24,000 specimens, some of which are accompanied by thin plates for microscopic observation, chemical analyses and extensive scientific observation.
This collection was assembled by Alfred Lacroix, professor of the Muséum national d’Histoire naturelle’s mineralogy chair from 1893 to 1936, partly by selecting samples from the collection of exogenous rocks. He used it to establish one of the first ever classifications of magmatic rocks following modern criteria (texture, mineralogical and chemical composition of the rocks) and to illustrate many geological phenomena (rock deformation, effect of lightning, rock alteration, eruptions of Mount Pelée). As well as this first group, rock specimens assembled in the first half of the 19th century were also added. The endogenous rock collection includes in particular the collection of F.S. Beudant (1787-1850).
Specimens chosen for their aesthetic appeal or their educational interest, which have been on display for a long time at the Galerie de Géologie et de Minéralogie (Gallery of Geology and Mineralogy), complete the collection.

In total, the collection is of great historic and scientific interest. It constitutes a unique petrographic inventory of the diversity of rocks in France and the former French colonial empire (Madagascar, West Africa and Asia).

Research
This collection remains an aid to scientific research, particularly due to the presence of many rare or now inaccessible rocks (deposits that have disappeared). It is of undeniable interest to anyone concerned with the History of Science. Along with its extensive iconography, the endogenous rock collection is accessible to all audiences upon request.