Jaipurite

Chemical formula: CoS

Jaipurite is a historical, now discredited sulfide mineral, which was supposed to be cobalt sulfide, but its existence has not been confirmed.

## Characteristics Jaipurite (jaipuryt) was originally described as cobalt sulfide (CoS) originating from copper mines in the Jaipur region of India. It was said to form fine, granular aggregates with a metallic luster and a steel-gray color with a pinkish hue. However, modern studies of material from the type locality have not confirmed the existence of a natural mineral with the composition CoS. Specimens historically identified as jaipurite turned out to be mixtures of other minerals, mainly cobaltite and pyrite. ## History and Name The mineral's name comes from its alleged discovery site in 1880, in the Jaipur district of Rajasthan, India. It was described by F.R. Mallet. Despite the historical description, the International Mineralogical Association (IMA) officially discredited jaipurite in 1982, as it was not possible to find and confirm the existence of a natural CoS phase corresponding to the original description.

Properties

Luster: Metallic
Streak: Blackish brown
Transparency: Opaque

Diagnostic features

## Identification Since jaipurite as a mineral does not exist, identification involves identifying the constituent minerals of historical samples. Look for characteristics of cobaltite (silver-white with a pinkish hue, often in the form of cubes or granular masses) and pyrite (brass-yellow, metallic luster). Identification requires advanced methods such as chemical analysis (EDS) or X-ray diffraction (XRD). ## Differentiation from Similar Minerals Historical "jaipurite" specimens are in fact mixtures. The main component, cobaltite, can be distinguished from other silvery sulfides by its hardness (5.5) and often cubic crystals. Pyrite is easily recognizable by its brass-yellow color.

Geological environment

## Genesis Synthetic cobalt sulfide (CoS) is known as a phase in metallurgy. The hypothetical conditions for the formation of natural jaipurite would involve hydrothermal environments rich in cobalt and sulfur, with low iron and arsenic content. However, such conditions that would allow for the crystallization of pure CoS in nature have not yet been found. ## Mineral Associations Based on the analysis of historical samples, minerals incorrectly identified as jaipurite co-occurred with cobaltite, pyrite, and chalcopyrite. ## Localities The only historically reported locality was the Khetri mines in the Jaipur district, Rajasthan, India. However, the status of this mineral as a distinct species has been challenged and ultimately rejected.

Rarity

Very rare

For collectors

## Quality Criteria Specimens labeled as "jaipurite" have only historical value. Their attractiveness lies not in aesthetic qualities, but in their connection to the history of mineralogy and the process of verifying new minerals. The most valuable specimens are those with original, old labels from the type locality (Khetri, India), dating from before the mineral's discreditation. The collector's value is sentimental and historical, not material.

Care and storage

## Cleaning Historical specimens, incorrectly identified as jaipurite, should be treated according to the properties of their constituent minerals (mainly cobaltite). Gentle wiping with a dry, soft cloth or brush to remove dust is usually sufficient. ## What to Avoid Avoid contact with water and chemicals, which could react with sulfides, leading to their oxidation and destruction. Protect them from moisture and extreme temperatures. ## Storage Store in a dry place, preferably in a closed display box or cabinet, to limit access to moisture and oxygen, which can cause sulfide degradation.

Sources

IMA Mineral List (CNMNC)