198 
PROCEEDINGS OF 
The soil of the hills, in the eastern part of Charlestown, abounds in fragments 
of slate, of a coarse texture, with numerous specks of black mica, and sometimes 
with small garnets, seemingly one of the varieties between argillaceous and mica 
slate. These fragments are of all sizes—from a mere pebble to the weight of many 
tons; some much worn, and others rough and angular, and with considerable dif¬ 
ference in fineness of texture. They are all characterized, however, by the presence 
of numerous crystals, of a curious character, which form the more immediate 
objects of this paper, and of which I have the pleasure to send the National Insti¬ 
tution a number of specimens ; an end of each of which I have cut and slightly 
polished, for the purpose of showing more readily the structure. 
These crystals have been variously denominated by different persons who have 
seen them, though no one appears to have given any careful description of them. 
One of the first persons who mentioned them to me, when I came into this part of 
the country to live, spoke of them as being crystals of staurotide; another after¬ 
wards called them made, (and they are so termed in Cleveland’s Mineralogy,) while 
Dr. Jackson, in the last report of his geological survey of New-Hampshire, speaks 
of them as made, or (apparently as synonymous) licmitropic andalusite. They 
are certainly of considerable variety of structure, under a general similarity of con¬ 
figuration ; and, while agreeing exactly with none of the minerals described under 
the foregoing names, have yet points of resemblance with each. 
Staurotide, or granatite, as called by some, belongs to the garnet family, and 
made and andalusite are of the feld-spar family, if made be, as I presume, the 
same as chiastolite, according to the nomenclature of Jameson. His description of 
the mineral, to which he gives this name, is, as far as my recollection serves, almost 
^precisely the same as that which Cleveland gives of made. 
The staurotide consists of two six-sided prisms, intersecting each other cither at 
•rio-ht angles or obliquely. The crystals in question are sometimes found in this 
form; and two of the specimens I send herewith, afford instances of it—one being 
an intersection nearly at right angles, and the other an oblique intersection, at about 
forty-five degrees. The generality of the crystals are, however, single, consisting 
of four-sided prisms, the bases of which are either rhomboids or rhombs. In the 
most perfect crystals, the latter shape is the prevalent one, and the figure is often 
very exact, the angles being extremely well defined. They have also a natural 
cleavage through the shorter diagonal of the rhomb, by which they are divided into 
two triangular prisms. Now liaiiy shows that the primitive form of granatite is a 
quadrangular prism, the bases of which are rhombs, with a similar cleavage through 
the shorter diagonal of the base. The angles of the rhombs he makes to be about 
130° and 50°, which agrees with the measurement of some of the most perfect of 
these crystals. 
Some of them also agree with staurotide in other external characters, as the 
dark reddish, brown color, the internal glimmering lustre between vitreous and re¬ 
sinous, in the general character of the fracture, in opacity, with occasional trans- 
lucency, in hardness, brittleness, and infusibifity. Yet still the specimens, in which 
these last characters are best marked, are precisely those which I have always 
found single, with rhombic or rhomboidal bases, and not intersecting each other. 
Those so intersecting have a different set of characters, apparently belonging more 
to the description of made or chiastolite, yet not precisely agreeing with that. 
