Occurrence
Azurite is rare at both Franklin and Sterling Hill. Although included in the earliest list of Franklin minerals, the first published description of it is that of the author (257) in 1928. The crystals were in thoroughly oxidized vein material found in the mine in pillar 720 on the 200-foot level. The small crystals, which line cavities in limonitic calcite along with malachite and fine rosettes of aurichalcite, are rich in forms. The crystals are elongated parallel to the orthoaxis with q(101) dominant in the orthodome zone, and they bear the forms of combinations 1 and 2, shown in figures 66 and 67.

Figure 66 Clinographic projection, rotated forward to show the base, of a crystal of azurite, prismatic parallel to the orthoaxis, showing the form c(001), a(100), p(021), y(101), q(301), m(110), and d(243). Franklin.
	Figure 67 Crystal of azurite tabular parallel to the base, showing the forms c(001), a(100), l(023), f(011), s(101), I(205), q(101), h(302), m(110), w(120), h(221), R(241), and e(245). Franklin. A, Plan; B, clinographic projection.

At Sterling Hill specimens of massive, coarse-granular franklinite ore were found intersected by veins of calcite and azurite that appear to have replaced the ore. As a whole azurite followed calcite, but the deposition of the two overlapped in part. The veins are generally granular, but a few cavities in the franklinite, representing the complete solution of large grains, are lined with brilliant crystals of azurite. Figure 68 illustrates a small doubly terminated crystal with ideal development of the forms of combination 2.

Figure 68 Crystal azurite showing the forms c(001), a(100), m(110), p(021), I(023), s(101), q(101), h(302), P(223), h(221), R(241), e(245) and (1.3.24). The figure is drawn with the orthoaxis in front instead of in the customary position. Sterling Hill. A, Plan; B, clinographic projection.

The form shown in the drawing as (1.3.24) is an etch face found symmetrically developed on most of the crystals. The form f :(034), not shown in the figure, was present with two faces. As this rare form requires confirmation its angle measurements are appended:

Figure 69 illustrates the habit of some paper-thin plates of azurite, flattened parallel to the base, with the forms of combination 3, the relative thickness of the crystal having been exaggerated in order to show the forms that are developed only as small faces.

Figure 69 Crystal of azurite thin-tabular parallel to the base, showing the forms c(001), b(010), a(100), m(110), p(021), s(101), q(101). Sterling Hill. A, Plan: B, clinographic projection.