Occurrence
Tourmaline is not a characteristic mineral of the zinc-ore bodies—indeed, it is unknown in them except for two brown crystals showing combinations 1 and 2, respectively, one each in the Canfield and Kemble collections. They were found in the calamine deposit at Sterling Hill but may well have been introduced there mechanically during the formation of the secondary calamine ore.

Figure 177 Stout prismatic crystal of tourmaline showing the forms c(0001), m(1010), a(1120), r(1011), r1(0111), and o(0221). Sterling Hill.

It is rather remarkable that tourmaline was not formed in the pneumatolytic zone of the Parker shaft, where all the conditions, including an intrusive magma rich in boron and fluorine, would lead one to expect its presence.

It is abundant, however, in the white limestone about Franklin. The most interesting locality is the Fowler quarry (see plate 1), where were found, many years ago, in a broad zone extending across the whole front of the quarry, crystals isolated in the limestone that were remarkable for their large size, perfection of form, brilliant coloring, and striking hemimorphic development. (See plate 17, A, and figures 178, 179, and 180.)

Figure 178 Stout prismatic crystal of tourmaline showing the forms a(1120), m(1010), m1(0110), o(0221), r1(1011), and c1(0001). Franklin.
	Figure 179 Stout prismatic crystal of tourmaline showing the forms m(1010), a(1120), r(1011), o(0221), c1(0001), r1(1011), and e1(0112). Fowler quarry, Franklin.
Figure 180 Thick-tabular crystal of tourmaline showing the forms c(0001), m(1010), a(1120), r(1011), e(0112), r1(1011), and o1(0221). Fowler quarry, Franklin.

They are commonly green, some of them bright grass-green on the surface and progressively lighter inward, others greenish yellow throughout. These crystals have not been analyzed, nor have such crystals been found in recent years. A few light brownish-yellow crystals of similar form have been found occasionally in a railroad cut in limestone near Franklin station.

In the Franklin Iron Company's quarry brown tourmaline is abundant in the limestone, with titanite, arsenopyrite, pyrrhotite, pyrite, fluorite, and other associates. Some of it is glassy and transparent, though apt to be flawed. Rarely are the large crystals well developed, but some of them show striking hemimorphism. Some of the crystals are highly complex—figures 181 and 182 show two that were studied.

Figure 181 Plan of a crystal of tourmaline showing the forms a(1120), m(1010), m1(0110), r(1110), y(4041), o(0221) and u(3251). Franklin Iron Company's quarry.
	Figure 182 Plan of a crystal of tourmaline showing the forms c(0001), a(1120), m(1010), m1(0110), r(1011), n(0113), e(0112), s(0332), o(0221), and t(2131). Franklin Iron Company's quarry.

Besides the determinable forms there are several facets which, although plane, do not have rational indices and are probably solution planes.

At Rudeville (Hamburg) the quarries have at times yielded abundant brown tourmaline crystals of forms similar to those of the crystals just described. Isolated crystals and crystal groups, some of them of many and large individuals, were seen in numerous collections. Eakle (162) described and figured these crystals, and Riggs (134) analyzed them.

Light-brown tourmaline associated with corundum was at one time found on Mine Hill. It was mistaken for vesuvianite and was widely distributed in collections, hence the erroneous presence of the name "vesuvianite" in the older lists of Franklin minerals.

Black tourmaline was not seen in the field or in any collection. Mr. Hancock stated, however, that he had seen specimens on Balls Hill, doubtless in the pegmatite abundant there.