CHAPTER I.
MINERALOGY AND GEOLOGY.
Minerals are found either in regular and geometrical forms when they are called cristals, or in more or less irregular masses.
Among cristals there are some so situated that they can be separated without injury from the matter that envelopes them. Others compose salient groups; others are imbedded in rock.
Specimens of each of these three States should, if possible be procured; with regard to cristals enveloped in surrounding matter, particles of this matter should be detached with them (varying from 8 to 10 centimetres) so that the different minerals which accompany them may be observed.
Also portions of the masses composed of needles and fibres, or granulous or compact, having care to choose them fresh and free from those alterations that take place in these at the surface. The metallic mines should call the attention of travellers. They will observe if they are in parallel beds with the surrounding rocks or in clefts called veins which cross the bed. In detaching pieces from these mines care should be taken to leave around the principal metal portions of other metals which may be associated with them or stony substances which often accompany cristals.
It is to be desired for the progress of historic and technical mineralogy that pieces of stone should be selected which are most commonly used in the construction of public monuments and houses; and the most authentic samples should be procured of all the mineral substances employed in the useful and ornamental arts; such as sharpening stones, stones for ovens, stones to polish with and stones for potteries; having care to indicate the kinds of earth and stones which enter into the composition of each kind of pottery; whether minerals are indigenous or exotic, it must be particulary mentioned from whence they come.
If organic remains should be found in these earths, such as the bones of animals, shells, impressions of fish or vegetables, samples should be taken with care from these different bodies, leaving around them a portion of the earth or stone in which they are imbedded.
In case these earths should offer traces of volcanic origin, pieces will be taken of each substance ejected by the explosions, some of a stony nature, some as basalts, some as glass, some as obsidiennes, some as scaries, etc. For those which are prisms, care must be taken to remark the form of these prisms and the extent they occupy in the earth.
To each sample should be attached a ticket indicating the name of the country where they were found, the particular spot from which they were taken, the distance and situation of some neighbouring known town from it, the nature and appearance of the country and its elevation above the sea.