Danielsite is a

sulfide Sulfide (British English also sulphide) is an inorganic anion of sulfur with the chemical formula S2− or a compound containing one or more S2− ions. Solutions of sulfide salts are corrosive. ''Sulfide'' also refers to chemical compounds lar ...

and

sulfosalt Sulfosalt minerals are sulfide minerals with the general formula , where *A represents a metal such as copper, lead, silver, iron, and rarely mercury, zinc, vanadium *B usually represents semi-metal such as arsenic, antimony, bismuth, and rarely ...

that was first discovered in a pocket of supergene minerals in the north region of

Western Australia Western Australia (commonly abbreviated as WA) is a state of Australia occupying the western percent of the land area of Australia excluding external territories. It is bounded by the Indian Ocean to the north and west, the Southern Ocean to th ...

. The location found was about west of the locality known as Coppin Pool. The mineral danielsite was named after John L. Daniels who collected the sample in which the new mineral was found. The chemical formula of danielsite is . Danielsite is very fine grained and hard to observe in hand samples. It generally has a gray color with very brittle and soft physical characteristics.

Occurrence

Danielsite occurs in the mineral anglesite as ragged polycrystalline masses typically intergrown with

covellite Covellite (also known as covelline) is a rare copper sulfide mineral with the formula CuS. This indigo blue mineral is commonly a secondary mineral in limited abundance and although it is not an important ore of copper itself, it is well known t ...

stromeyerite Stromeyerite is a sulfide mineral of copper and silver, with the chemical formula Ag Cu S. It forms opaque blue grey to dark blue orthorhombic crystals. It was discovered in 1832 in Central Bohemia Region, Czech Republic, and named after the Ge ...

, and

chalcocite Chalcocite (), copper(I) sulfide (Cu2S), is an important copper ore mineral. It is opaque and dark gray to black, with a metallic luster. It has a hardness of 2.5–3 on the Mohs scale. It is a sulfide with a monoclinic crystal system. The ...

. The size of these masses is typically across. Due to its occurrence with stromeyerite it is thought to possibly be a polymorphic replacement of galena. Danielsite was found in a gossanous pod in a white quartz vein. It has been found near Coppin Pool, Ashburton Shire, Western Australia, Australia, Austria, and Belgium.

Physical properties

Danielsite is a metallic-gray mineral that looks a lot like stromeyerite, the main difference between the two is that stormeyerites colors are yellow to brown whereas danielsite is gray. Danielsite is very soft and brittle with only a 1.5-2.5 on the

mohs hardness scale The Mohs scale of mineral hardness () is a qualitative ordinal scale, from 1 to 10, characterizing scratch resistance of various minerals through the ability of harder material to scratch softer material. The scale was introduced in 1812 by th ...

(VHN₁₀ hardness of 38). There is no discernible type of cleavage, but due to the small size of the crystallites the possibility of cleavage can't be 100% excluded. It is a rather dense mineral weighing in at 6.541 g/cm³.

Chemical composition

The data for this chart was gathered using a polished section by electron microprobe and using a crystal spectrometer with the following standards: galena (S), cinnabar (Hg), and metals (Ag and Cu). The results were calculated on the basis of 23 atoms due to its chemical formula being very similar to balkanite.

X-Ray crystallography

The sample found was ground up and an X-ray powder diffraction was done to the powder. The pattern had a few places that appeared to be anglesite but overall the pattern didn't match up with any other mineral known. Most of the values could be measured on a triclinic unit cell but the d values of the actual data and calculated data varied by a lot. Most sulfides do not belong to the triclinic system as well, so it was thought that this was the wrong choice for danielsite. More research was done on this mineral by Nickel and Kato and they both came to the conclusion that danielsite has an orthorhombic unit cell. When they tried calculating the d values based on the orthorhombic system the values came back very similar. Even though danielsite and balkanite have very similar chemical formulas their unit cells are vastly different. From the reported occurrences of the two minerals it is apparent that balkanite is the high temperature form and danielsite is the low-temperature form.

References

{{Authority control Sulfide minerals Sulfosalt minerals

Occurrence

Physical properties

Chemical composition

X-Ray crystallography

See also

References