Delchiaroite
A valid IMA mineral species
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About Delchiaroite
Formula:
Cu3I(CH3S)2
Colour:
light-yellow
Lustre:
Greasy
Specific Gravity:
3.565 (Calculated)
Crystal System:
Orthorhombic
Name:
Name honors the mineral collector Lorenzo Del Chiaro (b. 1951) for his contribution to the knowledge of the mineralogy of the vugs of the Marble Formation belonging to the Alpi Apuane metamorphic complex.
New structure type. Unique combination of elements (at the upload time).
Absolutely unprecedented as being - most likely - the first methanethiolate among the known mineral species.
Also represents the first iodorganic mineral to date.
Absolutely unprecedented as being - most likely - the first methanethiolate among the known mineral species.
Also represents the first iodorganic mineral to date.
Unique Identifiers
Mindat ID:
499362
Long-form identifier:
mindat:1:1:499362:5
IMA Classification of Delchiaroite
Approved
Approval year:
2026
Approval history:
IMA No. 2025-076
Type description reference:
Biagioni, Cristian; Sejkora, JiÅÃ; MoÃŦlo, Yves; Criscuolo, Antonino; DolnÃÄek, ZdenÄk (2026) When mineralogy meets the organic chemistry: delchiaroite, Cu 3 I(CH 3 S) 2 , the first copper iodideâmethanethiolate from the Carrara marble quarries, Apuan Alps, Tuscany, Italy. European Journal of Mineralogy, 38 (2). 153-167 doi:10.5194/ejm-38-153-2026
Classification of Delchiaroite
10.CB.10
10 : ORGANIC COMPOUNDS
C : Miscellaneous Organic Minerals
B : Methanethiolate
10 : ORGANIC COMPOUNDS
C : Miscellaneous Organic Minerals
B : Methanethiolate
Mineral Symbols
As of 2021 there are now IMAâCNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
| Symbol | Source | Reference for Standard |
|---|---|---|
| Dch | IMAâCNMNC | Warr, L.N. (2021). IMAâCNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
Physical Properties of Delchiaroite
Greasy
Transparency:
Transparent
Colour:
Light-yellow
Streak:
Light-yellow
Comment:
Hardness was not determined owing to the paucity of available material, but it should be soft.
Tenacity:
Brittle
Cleavage:
Perfect
perfect cleavage parallel to the crystal elongation
perfect cleavage parallel to the crystal elongation
Density:
3.565 g/cm3 (Calculated)
Optical Data of Delchiaroite
Anisotropism:
anisotropism is moderate, with gray tints
Reflectivity:
| Wavelength | R1 (%) | R2 (%) |
|---|---|---|
| 470nm | 20.6% | 22.2% |
| 546nm | 20.9% | 23.4% |
| 589nm | 20.7% | 23.3% |
| 650nm | 20.1% | 22.4% |
Graph shows reflectance levels at different wavelengths (in nm). Peak reflectance is 23.4%.
R1 shown in black, R2 shown in red
Colour in reflected light:
light gray
Internal Reflections:
abundant internal yellow reflections
Pleochroism:
Not Visible
Comments:
Pleochroism and bireflectance were not observed, maybe being masked by the strong internal reflections.
Comments:
Due to the very small amount of available material of delchiaroite, the optical properties were determined on the polished grains embedded in epoxy for electron microprobe analysis, determining its properties in reflected light.
Chemistry of Delchiaroite
Mindat Formula:
Cu3I(CH3S)2
Element Weights:
Crystallography of Delchiaroite
Crystal System:
Orthorhombic
Class (H-M):
mmm(2/m2/m2/m) - Dipyramidal
Space Group:
Pmmn
Setting:
Pmmn
Cell Parameters:
a = 16.924(10) Å, b = 4.099(2) Å, c = 5.572(3) Å
Ratio:
a:b:c = 4.129 : 1 : 1.359
Unit Cell V:
386.54 Ã
Âģ (Calculated from Unit Cell)
Z:
2
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 8.46 Ã | (100) |
| 3.989 Ã | (9) |
| 3.366 Ã | (12) |
| 3.315 Ã | (19) |
| 3.251 Ã | (6) |
| 2.362 Ã | (10) |
| 2.049 Ã | (7) |
| 1.947 Ã | (9) |
Locality:
Type Occurrence of Delchiaroite
General Appearance of Type Material:
acicular crystals, elongated on [010], up to 0.1âmm in length
Place of Conservation of Type Material:
the collections of (1) the Museo di Storia Naturale, University of Pisa, Via Roma 79, 56011 Calci (PI), Italy, catalogue number 20083, and
(2) the National Museum, CirkusovÃĄ 1740, 193 00 Prague 9, Czech Republic, catalogue number P1P 29/2025
(2) the National Museum, CirkusovÃĄ 1740, 193 00 Prague 9, Czech Republic, catalogue number P1P 29/2025
Geological Setting of Type Material:
related to the supergene alteration of enargite
Associated Minerals at Type Locality:
Reference:
Biagioni, Cristian; Sejkora, JiÅÃ; MoÃŦlo, Yves; Criscuolo, Antonino; DolnÃÄek, ZdenÄk (2026) When mineralogy meets the organic chemistry: delchiaroite, Cu 3 I(CH 3 S) 2 , the first copper iodideâmethanethiolate from the Carrara marble quarries, Apuan Alps, Tuscany, Italy. European Journal of Mineralogy, 38 (2). 153-167 doi:10.5194/ejm-38-153-2026
Synonyms of Delchiaroite
Other Language Names for Delchiaroite
Dutch:Delchiaroiet
Fluorescence of Delchiaroite
it does not fluoresce under both short- and long-wavelength ultraviolet radiations.
Other Information
Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.
Internet Links for Delchiaroite
mindat.org URL:
https://www.mindat.org/min-499362.html
Please feel free to link to this page.
Please feel free to link to this page.
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References for Delchiaroite
Reference List:
Biagioni, Cristian; Sejkora, JiÅÃ; MoÃŦlo, Yves; Criscuolo, Antonino; DolnÃÄek, ZdenÄk (2026) When mineralogy meets the organic chemistry: delchiaroite, Cu 3 I(CH 3 S) 2 , the first copper iodideâmethanethiolate from the Carrara marble quarries, Apuan Alps, Tuscany, Italy. European Journal of Mineralogy, 38 (2). 153-167 doi:10.5194/ejm-38-153-2026
Localities for Delchiaroite
Showing 1 localities.
symbol to view information about a locality.
The Locality List
- This locality has map coordinates listed.
- This locality has estimated coordinates.
â - Click for references and further information on this occurrence.
? - Indicates mineral may be doubtful at this locality.
- Good crystals or important locality for species.
- World class for species or very significant.
(TL) - Type Locality for a valid mineral species.
(FRL) - First Recorded Locality for everything else (eg varieties).
All localities listed without proper references should be considered as questionable.
Italy (TL) | |
| Biagioni et al. (2026) +1 other reference |
La Piana Quarry, Colonnata quarrying basin, Carrara, Massa-Carrara Province, Tuscany, Italy