Saturday morning found us outside the Ecole des Mines which is adjacent to the Luxembourg Gardens. Inside the building was like a mine with a maze of corridors and staircases but eventually we arrived at the museum. Once the entrance fees were paid the first sight to greet us was the illuminated cabinets all round the walls containing specimens of all sizes, shapes and colours. The most fragile, yet perfect, items from all over the world were on display and they must have been transported with such care to arrive intact.
 

History of the Collection
 

Later investigation of the history* behind the assembly of the collection explained why so many precious pieces came together. Stones, gems and salts were included in Louis XIIIs' pharmacy together with plants in what was later to be the Jardin du Roi, for possible use as cures in the hospitals. Once the "Kings Collection" began to be known precious items arrived as gifts from other Royal collections in Europe and Asia. 1745 saw the first opening for the public, about 5 years before the Louvre started. Similar collections were growing in other capitals.

A combined collection of minerals and geological items began and by the end of the next hundred years over 200,000 items made up the "working material". It was only the work of these museums and their dedicated staff that preserved these ordinary specimens in sufficient quantities to enable the studies to be done to lay the foundations of modern crystallography.

Mining destroys their "habitat" even more completely than chopping down rain forest. Most of the fine examples in the prize collection would have been rescued in the days when hand digging was used, and anyway they were too valuable to be used for everyday handling. The large machines, washing and blasting methods used today make the chance of finding interesting samples less likely.
 

Use of the Collection
 

Once the early collections started records and catalogues began and it was in doing this work that the studies were made to produce all the knowledge we now have about crystallography and minerals. Lectures and public instruction in alchemy and mineralogy were given in Paris as early as the C13 and work done by the Paris Mint on Gold and other precious metals all contributed to found the new studies into crystals and the composition of minerals. Rome de l'Isle did years of work measuring crystal forms and 1772 saw a first Standard Reference of crystal forms published. Gauges were made, clay models and the goniometer appeared all to produce the "constancy of angles" theory for identifying and classifying specimens. Improvements in equipment, weighing, analysing and the new accurate decimal system were used and the explorers of the expanding French Empire were supplying new minerals all the time. R.-J. Hauy worked for thirty years and established laws of symmetry, forms and facets and the whole mathematics of crystallography. The Ecole des Mines and the Museum of Natural History collections were added to and regrouped many times as classifications changed from crystal forms to chemical groups and then as now this is probably an endless task as more sophisticated techniques for analysing minerals appear.
 

Highlights
 

The "hands on" in the field side of the story of the explorers who visited sites all round the world is just as fascinating and obviously a topic all on its own. One end of the mineral gallery had a spectacular display of "hard rocks" with many polished slabs in the cases. A group of orbicular granites prompted a long discussion about their structures and formation mechanism. A young French student was drawn into the debate and we all aired our thoughts on the problem, if in rather basic English!. (If any one has any literature we would be interested).
 

Meteorites and Tektites
 

The collection of meteorites were on display in modern cabinets with raw samples, cut and polished sections and were accompanied by maps, diagrams and photographs of places where they were found and, in more recently documented falls, pictures of the damage caused to property. Meteorites help to provide information about the nature of matter from the earliest times when the Solar System was forming and most of the ones in collections are "finds" as it is obviously rare to witness a "fall". They are be more likely to be spotted in remote areas where the ground is relatively undisturbed and so it is no surprise that large numbers have come from ice fields in the Antarctic. A dark baked skin and high density for the size are initial indications of a possible "find" and cutting, polishing and etching reveal the distinctive crystal patterns especially of the larger numbers of Iron/nickel objects. These are features distinctive of low pressure formations possibly when the rocks were part of small bodies such as asteroids.

Stony meteorites can be divided into several groups according to iron content and of these Chondrites seem to be the most basic composition. Achondrites seem to have had some modification possibly from heating or impact while they were part of a larger object. Ejecta from large impacts on the Moon and Mars are also a possibility. Carbonaceous Chondrites are rarely found as they are friable so it is impossible to estimate their frequency among this group of "erratics" but they do contain organic compounds and amino acids. Much speculation has ensued as to any connections between these objects and the origins of life on Earth.

Finally the display included some tektites as they form from molten rock heated and ejected from an impact. They cool in the air into distinctive shapes and are found in "fields" some of which have later proved the location of an impact site. The party met up in the galleries again and by now it was approaching closing time and lunch. Everyone had found their favourite items and as always there was far more to see than the time allowed. We all are very grateful to Pat Bennett for her hard work in making the arrangements for the trip especially as there were a number of panics along the way and "computer bugs" gobbling tickets to contend with.

We were able to follow up in the afternoon with a visit to the Natural History Museum to see the Giant Crystals. Details of these later. See Here

*Giant Crystals and Precious Minerals. Henri-Jean Schubnel. Published by the Museum National d'Histoire Naturelle de Paris.