TERRIUM — A mineralogy cabinet

Esfalerita Cleiofana o Blenda acaramelada

Esfalerita is a mineral with formula (Zn,Fe)S, in the Sulfuros group. This specimen comes from Minas de Áliva, galería Esperanza, 4.º nivel («geodona»), Áliva, Camaleño, Cantabria, España and joined the Terrium collection in 2006.

Esfalerita Cleiofana o Blenda acaramelada from Minas de Áliva, galería Esperanza, 4.º nivel («geodona»), Áliva, Camaleño, Cantabria, España — Terrium

Description

Floater crystal of gem quality with caramel colour. In transmitted light it shows vivid amber to orange transparency and colour zoning. The main crystal, partially pyramidal and well-faceted, rises on a darker, compact base with visible reprecipitation zones.

History of this specimen

I closed the provenance of this piece—which was already good—by sheer luck: one night browsing the Mindat archive, I had a hunch when I thought I recognised my piece in an old photo of a pocket in situ. It was not easy to be sure because there were more pieces right there, freshly extracted and therefore dirty and dark. I contacted the collector, Carlos González Bargueño, who confirmed it: "You have a very good eye, that piece is the one in your collection. And I am glad it is yours." The human story behind it is like a film: Carlos had visited the mine from the outside since he was 11, dreaming of going in ever since a miner gave him a piece of sphalerite he still keeps. Years later he fulfilled that dream several times. On one of those, he extracted this jewel at personal risk: clandestine mining in mid‑winter, going in and out at night. Carlos recalls 14‑hour days at 5°C, constantly moving to keep warm, dodging collapses in a very unstable mine. It is the full cycle: from the child’s dream to my cabinet, with the geological "birth certificate" recovered by pure digital luck. (Mindat Photo ID 1030504) https://www.mindat.org/photo-1030504.html

About Esfalerita

Áliva sphalerite is world‑famous for its size and gem quality. The honeyed, transparent tones reflect the low iron content. It has a refractive index and dispersion (fire) higher than those of diamond, giving it an unmistakable adamantine lustre under good light. Because the deposit underwent remobilisation (natural tectonic movements) that shook the geodes, most crystals broke and many recrystallised on themselves; hence intact pieces like this are rare.

About the locality

At 1,603 m altitude, the Áliva Mines operated only in summer and reached down to −135 m on the sixth level. The best gem sphalerites came from the 2nd to 4th levels. The Esperanza gallery and its famous 'geodona' are legendary for having produced reference specimens now in leading museums. The area is now a National Park and collecting is prohibited. With the mine flooded, collapsed, and its entrances sealed with concrete since 2012, what is outside is all there will ever be.

Technical data

Catalogue No.
0232
Composition
(Zn,Fe)S
Name
Esfalerita
Variety
Cleiofana o Blenda acaramelada
Group
Sulfuros
Category
Cupidium
Mine
Minas de Áliva, galería Esperanza, 4.º nivel («geodona»)
District / Municipality
Áliva
Province
Camaleño
Region
Cantabria
Country
España
Size (cm)
7 x 5 x 2
Weight
95.4 g
Acquired
2006
Ex-collection
Carlos González Bargueño
Etymology
The name "sphalerite" (1847) is from Greek sphaleros, 'treacherous', echoing the older German miners’ name "Blende" ('deceiver') for its misleading metallic lustre. The variety "Cleiofana" was proposed by Thomas Nuttall c.1851, from Greek kleos (κλέος) 'glory, fame, renown' + phainesthai (φαίνεσθαι) 'to appear; to show oneself'—literally 'of glorious appearance'.
Quality
Muy buena
Value trend
Al alza

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