Editorial Feature

Jalpaite – Occurrence, Properties, and Distribution

May 7 2013

Jalpaite is a rare copper silver sulfide mineral that was discovered in the Leonora Mine, Jalpa, Mexico, and hence the mineral’s name reflects the location. It was found in 1858.

Properties of Jalpaite

The following are the key properties of jalpaite:

Cell Data
- Space group: I41/amd
- a = 8.663(0.8)
- c = 11.743(1)
- Z = 8
Crystal Data
- Tetragonal
- Point group: 4/m 2/m 2/m
- As coarse, irregular and foliated masses, to 5 cm
- As grains and veinlets in other sulfides
- X-ray powder pattern: 2.345 (100), 2.794 (90), 2.740 (80), 2.422 (80), 2.114 (70),
- 4.298 (60), 2.006 (60)

Chemical Composition

Elements	Content 1	Content 2	Content 3
Ag	71.51	71.7	71.71
Cu	13.12	14.05	14.08
S	14.36	[14.2]	14.21
Fe	0.79	-	-
Total	99.78	[100.0]	100.00

Optical Properties
- Pleochroism: Distinct in oil, brownish gray to pure gray
- Anisotropism: Distinct, in greenish blues and pale green
- R1–R2: (400) 33.5–34.6, (420) 34.4–34.9, (440) 35.1–34.8, (460) 35.4–34.2, (480) 35.2–33.4, (500) 34.4–32.8, (520) 33.7–32.4, (540) 33.0– 31.9, (560) 32.4–31.3, (580) 31.9–30.8, (600) 31.4–30.5, (620) 30.9–30.4, (640) 30.4–30.1, (660) 29.9–29.9, (680) 29.5–29.5, (700) 29.0–29.0

Estimated Properties

Electron density	Bulk density (electron density)=6.13 gm/cm³ note: Specific gravity of jalpaite =6.85 gm/cm³
Photoelectric	PE_Jalpaite = 190.00 barns/electron U=PE_Jalpaite x ρElectron density=1,165.13 barns/cm³
Fermion index	Fermion index = 0.0010658288 Boson index = 0.9989341712
Radioactivity	Jalpaite is not radioactive

How to Identify Jalpaite

Jalpaite can be identified in the field by its gray and dark gray variations and opaque quality. This mineral has metallic lustre with black streak. The density of jalpaite is 6.82 g/cm³ with a hardness of 2-2.5 – between gypsum and finger nail. The fractures occurring in this mineral are like curved shavings produced by a knife.

Global Distribution

Jalpaite is widely distributed in several locations. Some of the key locations are mentioned below:

USA -Colorado, at Payrock mine, Silver Plume, Clear Creek Co.; Bulldog Mountain mine, Creede, Mineral Co.; Hock Hocking mine, near Alma, Park Co.; from Boulder Co., at E.C. Hite mine, and Caribou mine, near Nederland, From Savage and Yellow Jacket mines, Comstock district, Storey Co., Nevada; at Mogollon, Catron Co., New Mexico
Australia -Broken Hill, New South Wales
Czech Republic -Bohutin and Vrancice deposit
Mexico- La Leonora mine, Jalpa, Zacatecas, and La Mesa,Chihuahua
Slovakia Zlata Bana deposit, Slanske vrchy Mountains
Ireland -Keel, Aedagh, Co. Longford
Norway- Kongsberg
France -Barreins, Aude
Italy -Boarezzo, Lombardy
Kazakhstan -Zavodinskii mine, near Ziryanovsk, Altai Mountains.
Japan- Sado mine, Niigata Prefecture, and the Koryu mine, Hokkaido

Occurrence of Jalpaite and Useful Mineral Association

Jalpaite forms in temperatures below 117°C (242°F) coupled with hydrothermal conditions. It is often associated with minerals such as galena, sphalerite, pyrite, acanthite, mckinstryite, chalcopyrite, silver, polybasite, stromeyerite, pearceite, and tetrahedrite–tennantite.