Editorial Feature

Neyite – Occurrence, Properties, and Distribution

Jun 3 2014

Neyite was named after Charles Stuart Ney, a geologist who was involved in the early exploration of the mineral at the Lime Creek deposit, Canada.

Properties of Neyite

The following are the key properties of neyite:

Cell Data
- Space group: C2/m
- a = 37.527(6)
- b = 4.0705(6)
- c = 43.701(7)
- β = 108.801(2)°
- Z = 4

Crystal Data
- Monoclinic
- Point group: 2/m
- As masses of small, intergrown crystals and grains
- As aggregates of prismatic to bladed crystals, with stepped surfaces on the wide faces, to 3mm (some prismatic aggregates might be twisted and curved)
- X-ray powder pattern: 3.72 (10), 3.51 (10), 2.92 (10), 2.04 (6), 2.27 (5), 2.08 (4), 1.461 (4)

Chemical Composition

Elements	Content 1	Content 2	Content 3
Pb	41.76	37.9	38.68
Bi	36.62	40.4	40.58
S	15.65	16.2	16.28
Cu	2.84	2.9	2.85
Ag	1.52	1.58	1.61
Cd	-	0.3	-
Sb	-	0.1	-
Total	98.39	99.4	100

Optical Properties
- Anisotropism: Medium. Pale gray, yellow-green, and pale reddish-brown to gray-black
- R1–R2: (400) 41.3–44.5, (420) 41.6–44.8, (440) 41.8–45.0, (460) 42.1–45.2, (480) 42.3–45.3, (500) 42.4–45.0, (520) 42.2–45.1, (540) 41.9– 44.8, (560) 41.6–44.5, (580) 41.4–44.4, (600) 41.2–44.5, (620) 41.0–44.6, (640) 40.7–44.6, (660) 40.4–44.5, (680) 40.2–44.3, (700) 39.9–44.1

Estimated Properties

Electron density	Bulk density (electron density) = 5.79 gm/cm³ note: Specific gravity of neyite = 6.96 gm/cm³
Photoelectric	PE_Neyite = 1,500.32 barns/electron U = PE_Neyite x ρElectron density = 8,684.44 barns/cm³
Fermion index	Fermion index = 0.08 Boson index = 0.92
Radioactivity	Neyite is not radioactive

How to Identify Neyite

Neyite can be identified in the field by its color variations, such as lead-gray, silver-gray, gray-blue, and yellow-blue. Its opaque form has no cleavage. This mineral has a metallic lustre with gray streak. The fracture on this mineral is brittle-conchoidal.

The density of neyite is 7.02 g/cm³, with a hardness of 2.5 – approximate to finger nail.

Global Distribution

Neyite is distributed in the following places:

Canada - Patsy Creek, Kitsault, near Alice Arm, British Columbia
USA - Johnny Lyon Hills, north of Benson, Cochise Co. Arizona; Alaska mine, Poughkeepsie Gulch, San Juan Co. Colorado; Whiskey Canyon prospect, Lewis district, Lander Co. Nevada
Zimbabwe - Golconda prospect, Chishawasha, near Harare
Portugal - Vale das Gatas tungsten mine, near Vila Real
Austria - Felbertal tungsten mine, Salzburg

Occurrence of Neyite and Useful Mineral Association

Neyite occurs in the late-forming, cross-cutting hydrothermal quartz veins in a quartz-molybdenite stockwork. It also occurs in the mesozonal synmetamorphic quartz veins.

It is often associated with minerals such as pyrite, chalcopyrite, aikinite, galena, sphalerite, cosalite, tetrahedrite, molybdenite, gold, nuffieldite, chalcopyrite, nordstromite, and quartz.