This section is from "Scientific American Supplement Volumes 275, 286, 288, 299, 303, 312, 315, 324, 344 and 358". Also available from Amazon: Scientific American Reference Book.
By NELSON H. DARTON.
There will be many persons in the city of New York and its suburbs who will not have the time or facilities for leaving town during the summer, to spend a part of their time enjoying the country, but would have sufficient time to take occasional recreation for short periods. I have sought by this paper to show a pleasurable, and at the same time very instructive use for the time of this latter class, and that is in mineralogy. In the surrounding parts of New York are many mineralogical localities, known to no others than a few professional mineralogists, etc., and from which an excellent assortment of minerals may be obtained, which would well grace a cabinet and afford considerable instruction and entertainment to their owner and friends, besides acting as an incentive to a further study of this and the other sciences. These localities which I will discuss are all within an hour's ride from New York, and the expenses inside of a half dollar, and generally very much less. I could detail many other places further off, but will reserve that for another paper.
The course which I will pursue in my explanations I have purposely made very simple, avoiding--or when using, explaining--all technical terms. The apparatus and tests noticed are of the most rudimentary style consistent with that which is necessary to attain the simple purpose of distinguishment, and altogether I have prepared this paper for those having at the present time little or no knowledge or practice in mineralogy, while those having it can be led perhaps by the details of the localities noticed. Another reason why I have written so in detail of this last subject is, because the experiences of most amateur mineralogists are generally so very discouraging in their endeavors to find the minerals, and there is everything in giving a good start to properly fix the interest on the subject. The reason of these discouragements is simple, and generally because they do not know the portion of the locality, say, for instance, a certain township, in which the minerals occur. And if they do succeed in finding this, it is seldom that the portion in which the mineral occurs, which is generally some small inconspicuous vein or fissure, is found; and even in this it is generally difficult to recognize and isolate the mineral from the extraneous matter holding it. As an instance of this I might cite thus: Dana, in his text book on mineralogy, will mention the locality for a certain species, as Bergen Hill--say for this instance, dogtooth calespar. When we consider that Bergen Hill, in the limited sense of the expression, is ten miles long and fully one mile wide, and as the rock outcrops nearly all over it, and it is also covered with quarries, cuttings, etc., it may be seen that this direction is rather indefinite. To the professional mineralogist it is but an index, however, and he may consult the authority it is quoted from--the American Journal of Science, etc.--and thus find the part referred to, or by consulting other mineralogists who happen to know. Again, the person having found by inquiry that the part referred to is the Pennsylvania Railroad, and as this is fully a mile long and interspersed with various prominent looking, but veins of a mineral of little value, at any rate not the one in question, they are few who could suppose that it occurred in that. Apparently a vein of it would not be noticed at all from the surrounding rock of gravelly earth, but there it is, and in a vein of chlorite. This is so throughout the long and more or less complete stated lists of mineralogical localities. Thus I will, in describing the mineral, after explaining the conditions under which it occurs, give almost the exact spot where I have found the same mineral myself, and have left sufficiently fine specimens to carry away, and thus no time will be lost in going over fruitless ground, and further, this paper is written up to the date given at its end, insuring a necessary presence of them.
In order that one not familiar with mineral specimens should not carry off from the various localities a variety of worthless stones, etc., which are frequently more or less attractive to an inexperienced eye, the following hints may be salutary.
There are the varieties of three minerals, which are very commonly met with in greater or less abundance in mineralogical trips: they are of calcite, steatite, and quartz. They occur in so many modifications of form, color, and condition that one might speedily form a cabinet of these, if they were taken when met with, and imagine it to be of great value. The first of these is calcite. It occurs as marble, limestone; calcspar, dogtooth spar, nail head spar, stalactites, and a number of other forms, which are only valuable when occurring in perfect crystals or uniquely set upon the rock holding it. The calcspar is extremely abundant at Bergen Hill, where it might be mistaken for many of the other minerals which I describe as occurring there, and even in preference to them, to one's great chagrin upon arriving home and testing it, to find that it is nothing but calcite. In order to avoid this and distinguish this mineral on the field, it should be tested with a single drop of acid, which on coming in contact with it bubbles up or effervesces like soda water, seidlitz powder, etc., while it does not do so with any of the minerals occurring in the same locality. This acid is prepared for use as follows: about twenty drops of muriatic acid are procured from a druggist in a half-ounce bottle, which is then filled up with water and kept tightly corked. It is applied by taking a drop out on a wisp of broom or a small minim dropper, which may be obtained at the druggist's also. I do not say that in every case this mineral should be rejected, because it is frequently very beautiful and worthy of place in a cabinet, but should be kept only under the conditions mentioned further on in this paper, under the head of "Calcite in Weehawken Tunnel."
The next mineral abundant in so many forms is quartz, and is not so readily distinguished as calcite. It is found of every color, shape, etc., possible, and that which is found in any of the localities I am about to describe, with the exception of fine crystals on Staten Island, are of no value and may be rejected, unless answering in detail to the description given under Staten Island. The method of distinguishing the quartz is by its hardness, which is generally so great that it cannot be scratched by the point of a knife, or at least with great difficulty, and a fragment of it will scratch glass readily; thus it is distinguished from the other minerals occurring in the localities discussed in this paper.
The other minerals so common are the varieties of steatite. This is especially so at Bergen Hill and Staten Island. They occur in amorphous masses generally, and may be distinguished by being so soft as to be readily cut by the finger nail. I will detail further upon the soapstone forms in discussing the localities on Staten Island, and the chloritic form under the head of "Weehawken Tunnel." The surest method of avoiding these and recognizing the others by their appearance, which is generally the only guide used by a professional mineralogist, is to copy off the lists of the various minerals I describe, and, by visiting the American Museum of Natural History on any week day except Mondays and Tuesdays, one may see and become familiar with the minerals they are going in quest of, besides others in the cases. This method is much more satisfactory than printed descriptions, and saves the labor of many of the distinguishing manipulations I am about to describe, besides saving the trouble of bringing inferior specimens of the minerals home.
In going forth on a trip one should be provided with a mineralogical hammer, or one answering its purpose, and a cold chisel with which to detach or trim the minerals from adhering rocks, the bottle of acid before referred to, and a three cornered file for testing hardness, as explained further on. As I noticed before, the better plan of distinguishing a mineral is by being familiar with its appearance, but as this is generally impracticable, I will detail the modes used in lieu of this to be applied on bringing the minerals home. These distinguishments depend on difference in specific gravity, hardness, solubility in hot acids, and the action of high heat. I will explain the application of each one separately, commencing with--