Delve into the genetic secrets of Afghan Panjhir emeralds

LIU Lihong, Andrew Lucas and trusted local Afghan friends on their way to the emerald mines in the Panjshir Valley, which are rugged and over 4,000 metres above sea level. Copyright © GUILD Gem Academy

In ancient Roman and Greek times, Afghan emeralds were already known. But it wasn't until the 1970s that modern excavations began in the Panjshir Valley. As emeralds from the Panjshir region of Afghanistan have rapidly become upstarts and even generated market premiums in recent years, the industry's curiosity about the region has been amplified[1] and has received more and more attention and recognition.

Geological background of the deposit

Afghanistan is mountainous, stretching along the Himalayan Hindu Kush Mountains, with mountains and plateaus covering four-fifths of the country.[1][3] As one of the five great mountains of Central Asia, the Hindu Kush Mountains are the dividing line between the Eurasian Plate and the Indian Ocean Plate, where geological activity is more active and complex.

The panjshir valley is famously located on the southeastern side of the valley near the Khihj region, the canyon runs along the Panjshir River, and the emerald mines are distributed in the surrounding mountains, with an elevation of between 2,000 and 4,000 m above sea level.

The rock formations of panjhir emerald veins include metamorphic limestone, calcareous slate, thousand rocks, mica schist, etc. formed during the Silurian-Devonian period 400 million years ago. Panjhir emeralds are scattered in quartz-dolomite-pyrite veins with a maximum width of 15 cm. This vein emerald is hydrothermal and is formed by chemical reactions along the vein solution and surrounding rock [5].

The typical emerald mine appearance in the mountains surrounding the Panjhir Valley, with visible tunnels, tents, and housing for emerald miners. (Andrew Lucas Photography); Copyright © GUILD Gem Academy

Gemologists from guild gem laboratories visited the Panjshire mine in 2019 and collected a large number of A-type samples, and the experience of the mine expedition is recorded in the book "The Gem Journey: From Mine to Market".

Gem Journey: From Mining To Market book

Conventional gemological properties

Panjhir emerald rough visible crystals mostly develop into hexagonal long columns, visible {101-0} hexagonal columns and {0001} bottom surface[4], parallel to the hexagonal column crystal surface longitudinal patterns, shell-like fractures, common obvious color bands and color rings, visible color block partitions. Some samples can see cleavage {0001} directions distributed in parallel. Blue-green/green under the dichroic mirror, most of the samples turn red under the Charles filter, and a weak to medium red color is visible.

Conventional gemological features of Afghan emeralds

project	Gemological characteristics
color	Light green to dark green, often with a bluish hue
Crystallization habit	Hexagonal long column, {101-0} hexagonal column and {0001} bottom surface[4], crystal plane longitudinal pattern, shell-like fracture, parallel ribbon, hexagonal color ring, color block partition, etc
RE	1.577-1.588
DR	0.006-0.011
Cleavage	Incomplete bottom cleavage
pleochroism	Blue-green/green, dichroic
Color filters	Most of them turn red, and a weak to medium red color is visible
fracture	Shell-like fractures

Microscopic observation

、

Internal inclusions

Gas-liquid-solid multiphase inclusions are extremely rich, commonly showing tooth-like, elongated, elongated tubular, etc., of which multiple solid small crystals are common. Visible "oil droplet"-like, flat, toothed and multi-nucleated growth structures can be seen.

Common rhomboid dolomite monocrystalline or crystal clusters, granular or irregular plate flake calcite, hexagonal single cone quartz, hunky lump or irregular column pyrite, short column or cluster rutile, opaque hematite, sulfur attached to the surface of pyrite and so on.

Causes of colorogenesis

The beautiful color exhibited by Afghan emeralds is caused by trace colorogenic elements inside. Studies have shown that the color-causing elements of emerald are mainly Cr, V, fe. The ultraviolet-visible spectrum of Panjhir emerald shows that the main absorption peaks are 370 nm, 430 nm, 620 nm, 682 nm, 840 nm and other characteristic peaks.

UV-visible spectrum of Panjhir emerald in Afghanistan

Interpretation of the report

For nearly 40 years, the GUILD Gem Lab has collected a large number of Afghan emerald Class A specimens, accumulated massive test data, and established and improved a gem database. Since 2020, the GUILD Gem Laboratory has been producing reports on small production areas in the Panjshir mining area of Panjshir in Afghanistan.

Panjshir Emeralds, Panjshir, Afghanistan, reports On Samle

bibliography

[1] Andrew. Lucas, Liu Lihong,Zhou Dan. Gem Journey[M].Xiangjiang Science Press, 2020.

Qi Shijun. Mineralization characteristics of Xingdu Kushi-West Kunlun area[J].Xinjiang Geology.2013(4):313-317.

[3] Fijal J,Heflik W ,Natkaniec-Nowak L , et al. Emeralds from the Panjshir Valley (Afghanistan). 2004.

Li Shengrong, Xu Hong, Shen Junfeng. Crystallography and mineralogy[M]. Geological Publishing House, 2008.

Delve into the genetic secrets of Afghan Panjhir emeralds

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