Information about Creedite

Creedite is a rare calcium aluminium sulphate fluoride hydroxide mineral, most immediately recognisable – in its finest form – by its spectacular radiating clusters of colourless to pale purple or pale orange acicular crystals.

It belongs to a small group of calcium sulphate-fluoride minerals that form in the oxidised zones of fluorite-bearing polymetallic sulphide deposits, particularly where sulphate ions from sulphide oxidation interact with fluorine released from fluorite. The result is a chemically unusual mineral that bridges the sulphate and fluoride mineral classes.

The finest specimens in my opinion come from Mexico – both from the Navidad Mine and the Santa Eulalia mining district. Other fantastic sources include the Hall Molybdenum Mine in Nevada, USA and the Akchatau Mine, Kazakhstan.

Creedite crystals are typically acicular (needle-like) to prismatic, arranged in diverging radiated sprays or stellate clusters that give the mineral an immediately distinctive appearance under any light. The crystals are typically small – a few millimetres to rarely over 1 cm – but the purity of colour and radial geometry of the best Mexican specimens make them some of the most visually striking of all the rarer sulphate-fluoride minerals.

Uses and History

Creedite has no industrial applications. It is collected as a specimen mineral, with the finest quality material from Mexican fluorite mines among the most sought-after of the rarer sulphate species.

The mineral was first described in 1916 from specimens collected at the Creede quadrangle in Mineral County, Colorado, USA – its type locality and namesake. The Creede area was an important 19th-century silver mining camp, and creedite occurs there in the oxidised fluorite-bearing veins associated with the hydrothermal silver mineralisation.

Mineralogy

Hazards and Warnings

Contains fluorine: creedite is a fluoride-bearing mineral. Fine dust should not be inhaled, and hands should be washed after handling. Under normal specimen handling conditions, fluoride minerals present no acute hazard.

Almost all rocks, minerals (and, frankly, almost all other substances on earth) can produce toxic dust when cutting, which can cause serious respiratory conditions including silicosis. When cutting or polishing rocks, minerals, shells, etc, all work should be done wet to minimise the dust, and a suitable respirator or extraction system should be used.

Translations

Further Reading / External Links

• https://en.wikipedia.org/wiki/Creedite
• https://www.mindat.org/min-1156.html
• https://www.handbookofmineralogy.org/pdfs/creedite.pdf