Chapter 13B. Analysis of Imaging Spectrometer Data for the 

Panjsher Valley Area of Interest

By Raymond F. Kokaly and Stuart A. Giles

Abstract

Imaging spectrometer data collected over the Panjsher Valley area of interest (AOI) in 

northeastern Afghanistan were analyzed with spectroscopic methods to identify the occurrence of 

selected material classes at the surface. Absorption features in the spectra of HyMap data were 

compared to a reference library of spectra of known materials. Carbonates and muscovites cover most of 

the Panjsher Valley AOI. Chlorite/epidote is also found distributed in spatially contiguous areas. The 

serpentine class was mapped in spatially coherent patches dotting the AOI, with the larger patches north 

of the valley bottom. Linear zones with small groupings of dolomite, calcite and dolomite or serpentine, 

and serpentine classes occur within Silurian-Devonian and Ordovician rocks, stretching along a coherent 

trend greater than 16 kilometers long in the southern portion of the subarea. The emeralds and 

pegmatites present in the southeastern zone (Khainch, Mikeni, Butak, and Darkhenj) are all located 

along this trend. The calcite and dolomite classes detected in the imaging spectrometer data could be 

defining the contact between Silurian–lower Carboniferous carbonate rocks, and upper Carboniferous–

Permian flysch rocks associated with the emerald and pegmatite mineral occurrences. A large area that 

does not match well to the reference entries in the spectral library used in this preliminary analysis was 

found. In general, the reflectance level in the longer wavelengths of rocks in these areas are low 

compared to surrounding areas, making them appear quite distinct in a false-color composite of HyMap 

bands. The spectra in these areas have two absorption features at varying strength, a narrow feature 

centered near 2.115 micrometers and a broad feature centered near 2.338 micrometers, which could arise 

solely from minerals or from minerals and overlying vegetation. Because of their proximity to the 

emerald occurrences, additional work to define the composition of rocks in these areas is warranted in 

conjunction with further analysis to identify their spectra and define their distribution in the imaging 

spectrometer data. A small concentration of hematite was identified in the Panjsher Valley AOI 

(lat 35.568289°N., long 69.891194°E.). This is surrounded by a large area of pixels (more than 44 

square kilometers) that were matched to fine- and medium-grained goethite, and iron hydroxide, which 

spans Silurian–Devonian and Early Proterozoic mapped rock units. The known iron mineral occurrences 

are found within the area defined by the mapped hematite, goethite, and iron hydroxide minerals.

13B.1 Introduction

Past studies of geologic data of Afghanistan revealed numerous areas with indications of 

potential mineral resources of various types (Peters and others, 2007; Abdullah and others, 1977).

Several of these potential mineral resource areas were selected for follow-on studies using imaging 

spectroscopy to characterize surface materials. Imaging spectroscopy is an advanced type of remote 

sensing also known as hyperspectral remote sensing. One of the selected areas is the Panjsher Valley 

area of interest (AOI) in northeastern Afghanistan, which is approximately 120 kilometers (km)

northeast of Kabul (fig. 13B–1). This area has been mined for emeralds and has the potential for silverbearing iron ores (Peters and others, 2007). To help assess these potential resources, high-resolution 

imaging spectrometer data were analyzed to detect the presence of selected minerals that may be 

indicative of past mineralization processes. This report contains the results of the spectroscopic data 
1018 Summaries of Important Areas for Mineral Investment and Production Opportunities of Nonfuel Minerals in Afghanistan

analyses and identifies numerous sites within the Panjsher Valley AOI that warrent further investigation, 

especially detailed geological mapping, lithologic sampling, and geochemical studies.

Figure 13B–1. Location map of the Panjsher Valley area of interest in northeast Afghanistan.

13B.2 Data Collection and Processing

In 2007, imaging spectrometer data were acquired over most of Afghanistan as part of the 

U.S. Geological Survey (USGS) project “Oil and Gas Resources Assessment of the Katawaz and 

Helmand Basins.” These data were collected to characterize surface materials in support of assessments 

of resources (coal, water, minerals, and oil and gas) and earthquake hazards in Afghanistan (King and 

others, 2010). Imaging spectrometers measure the reflectance of visible and near-infrared light from the 

Earth’s surface in many narrow channels, producing a reflectance spectrum for each image pixel. These 

reflectance spectra can be interpreted to identify absorption features that arise from specific chemical 

transitions and molecular bonds that provide compositional information about surface materials. 

Imaging spectrometer data can only be used to characterize the upper surface materials and not 

subsurface composition or structure. However, subsurface processes can be indicated by the distribution 

of surface materials that can be detected using imaging spectroscopy data.

13B.2.1 Collection of Imaging Spectrometer Data

The HyMap imaging spectrometer (Cocks and others, 1998) was flown over Afghanistan from 

August 22 to October 2, 2007 (Kokaly and others, 2008). HyMap has 512 cross-track pixels and covers 

the wavelength range 0.43 to 2.48 micrometers (μm) in 128 channels. The imaging spectrometer was 
Chapter 13B. Analysis of Imaging Spectrometer Data for the Panjsher Valley Area of Interest 1019

flown on a WB-57 high-altitude aircraft at 50,000 ft. There were 207 standard data flight lines and 11 

cross-cutting calibration lines collected over Afghanistan for a total of 218 flight lines, covering a 

surface area of 438,012 square kilometers (km2

) (Kokaly and others, 2008). Data were received in scaled 

radiance form (calibrated to National Institute of Standards and Technology reference materials). Before 

processing, four channels that had low signal-to-noise ratios and (or) were in wavelength regions 

overlapped by adjacent detectors were removed from the HyMap data. Each flight line was 

georeferenced to Landsat base imagery in UTM projection (Davis, 2007). 

13B.2.2 Calibration

HyMap data were converted from radiance to reflectance using a multi-step calibration process. 

This process removed the influence of the solar irradiance function, atmospheric absorptions, and 

residual instrument artifacts, resulting in reflectance spectra that have spectral features that arise from 

the material composition of the surface. Because of the extreme topographic relief and restricted access 

to ground-calibration sites, modifications to the standard USGS calibration procedures were required to 

calibrate the 2007 Afghanistan HyMap dataset (Hoefen and others, 2010). In the first step of the 

calibration process, the radiance data were converted to apparent surface reflectance using the radiative 

transfer correction program Atmospheric CORrection Now (ACORN; ImSpec LLC, Palmdale, Calif.).

ACORN was run multiple times for each flight line, using average elevations in 100-meter (m) 

increments, covering the range of minimum to maximum elevation within the flight line. A single 

atmospherically corrected image was assembled from these elevation-incremented ACORN results. This 

was done by determining the elevation of each HyMap pixel and selecting the atmospherically corrected 

pixel from the 100-m increment closest to that elevation. 

Each assembled atmospherically corrected image was further empirically adjusted using groundbased reflectance measurements from a ground-calibration site. Five ground-calibration spectra were 

collected in Afghanistan: Kandahar Air Field, Bagram Air Base, and Mazar-e-Sharif Airport, as well as, 

soil samples from two fallow fields in Kabul. At each site, the average field spectrum of the ground 

target was used to calculate an empirical correction factor using the pixels of atmospherically corrected 

HyMap data in the flight lines that passed over the site. Subsequently, each of the HyMap flight lines 

was ground-calibrated using the empirical correction from the closest calibration site. 

To further improve the data quality, an additional calibration step was taken to address the 

atmospheric differences caused, in part, by the large distances between the calibration sites and the 

survey areas. The large distances were a result of the lack of safe access to ground-calibration sites. The 

duration of the airborne survey and variation in time of day during which flight lines were acquired also 

resulted in differences in atmospheric conditions between standard flight lines and lines over groundcalibration sites, which were used to derive the empirical correction factors. Over the course of the data 

collection, the sun angle, atmospheric water vapor, and atmospheric scattering differed for each flight 

line. To compensate for this, cross-cutting calibration flight lines over the ground-calibration areas were 

acquired (Kokaly and others, 2008) and used to refine the reflectance calculation for standard data lines. 

A multiplier correction for standard data lines, typically oriented as north-south flight lines, was derived 

using the pixels of overlap with the well-calibrated cross-cutting lines, subject to slope, vegetation 

cover, and other restrictions on pixel selection (Hoefen and others, 2010). As a result, the localized 

cross-calibration multiplier, derived from the overlap region, reduced residual atmospheric 

contamination in the imaging spectrometer data that may have been present after the ground-calibration 

step. 

13B.2.3 Materials Maps and Presentation

After undergoing the above calibration process, the georeferenced and calibrated reflectance data 

were processed. The reflectance spectrum of each pixel of HyMap data was compared to the spectral 

features of reference entries in a spectral library of minerals, vegetation, water, and other materials 
1020 Summaries of Important Areas for Mineral Investment and Production Opportunities of Nonfuel Minerals in Afghanistan

(King and others, 2011; Kokaly and others, 2011). The best spectral matches were determined for each 

pixel, and the results were clustered into classes of materials discussed below. 

HyMap reflectance data were processed using MICA (Material Identification and 

Characterization Algorithm), an Interactive Data Language (IDL) module of the U.S. Geological Survey 

PRISM (Processing Routines in IDL for Spectroscopic Measurements) software (Kokaly, 2011). The 

MICA analysis compared the reflectance spectrum of each pixel of HyMap data to entries in a reference 

spectral library of minerals, vegetation, water, and other materials. The HyMap data were compared to 

97 reference spectra of well-characterized mineral and material standards. The resulting maps of 

material distribution, resampled to a 23×23-meter-square pixel grid, were mosaicked to create thematic 

maps of surface mineral occurrences over the full dataset covering Afghanistan. 

MICA was applied to HyMap data twice to present the distribution of two categories of minerals 

that are naturally separated in the wavelength regions of their primary absorption features. MICA was 

applied using the subset of minerals with absorption features in the visible and near-infrared wavelength 

region, producing a 1-μm map of iron-bearing minerals and other materials (King and others, 2011), and 

again using the subset of minerals with absorption features in the shortwave infrared, producing a 2-μm 

map of carbonates, phyllosilicates, sulfates, altered minerals, and other materials. For clarity of 

presentation, some individual classes in these two maps were bundled by combining selected mineral 

types (for example, all montmorillonites or all kaolinites) and representing them with the same color in 

order to reduce the number of mineral classes. The iron-bearing minerals map has 28 classes. Ironbearing minerals with different mineral compositions but similar broad spectral features are difficult to 

classify as specific mineral species. Thus, generic spectral classes, including several minerals with 

similar absorption features, such as Fe3+ type 1 and Fe3+ type 2, are depicted on the map. The 

carbonates, phyllosilicates, sulfates, and altered minerals map has 32 classes. Minerals with slightly 

different compositions but similar spectral features are less easily discriminated, thus, some identified 

classes consist of several minerals with similar spectra, such as the chlorite or epidote class. When 

comparisons with reference spectra provided no viable match, a designation of “not classified” was 

assigned to a pixel.

13B.3 Geologic Setting

The Panjsher Valley AOI is in the Parwan Province in northeastern Afghanistan. The contrastenhanced stretch of the natural-color composite of Landsat Thematic Mapper bands in figure 13B–2 

provides a general overview of the Panjsher Valley AOI terrain and is useful for understanding the 

general characteristics and distribution of surficial material including rocks and soil, unconsolidated 

sediments, vegetation, and hydrologic features. 

13B.3.1 Topography

Elevations in the Panjsher Valley AOI range between 2,070 and 5,041 m (fig. 13B–3). The 

lowest area runs through the center of the Panjsher Valley AOI between sharply defined mountain 

ranges and foothills that are commonly controlled by faults. The district center of Chahar Qarya lies in 

the valley near the southwest edge of the AOI. The high areas are on the edges of the Panjsher Valley 

AOI in sharply defined mountain peaks. 

13B.3.2 Lithology and Structure

The oldest rocks in the Panjsher Valley AOI are Early Proterozoic stratified rocks, including 

micas, biotites, amphiboles, marbles, schists and quartzites (fig. 13B–4; Doebrich and others, 2006; 

Abdullah and Chmyriov, 1977). These rocks are mapped over the majority of the AOI. Younger 

Silurian–Devonian stratified rocks, limestones and dolomites, and Ordovician limestones, sandstones, 

siltstones, and chert run through the middle of the Panjsher Valley AOI in a southwest to northeast 

orientation. Pennsylvanian and Early Permian stratified rocks are exposed at the highest elevations along 
Chapter 13B. Analysis of Imaging Spectrometer Data for the Panjsher Valley Area of Interest 1021

the western portion of the northern edge of the AOI. Intrusive rocks of Oligocene to Proterozoic age 

occur throughout the area. 

13B.3.3 Known Mineralization

Figure 13B–5 shows 17 locations where mineralization with a potential for mineral resource 

development may exist (Peters and others, 2007). Occurrences of emeralds and silver-bearing iron ores 

have been described within the Panjsher Valley AOI. The mineralogical characteristics of the 

mineralized locations are summarized in table 13B-1. 

Figure 13B–2. Contrast-enhanced Landsat Thematic Mapper natural-color image of the Panjsher Valley area of 

interest. Geologic contacts and faults from (Doebrich and others, 2006; Abdullah and Chmyriov, 1977).

The known emerald deposits of the Panjsher Valley lie along the southeastern side of the valley 

near the village of Khenj (Kazmi and Snee, 1989; Bowersox and others, 1991), although emeralds also 

are present on the northwest side of the valley (Samarin and Akkermantsev, written commun. to Afghan 

Ministry of Mining and Industries, 1977). Emerald mineralization is localized along linear zones that 
1022 Summaries of Important Areas for Mineral Investment and Production Opportunities of Nonfuel Minerals in Afghanistan

contain fracturing and brecciation of hydrothermally altered gabbro-diorite dikes, marble, schist, and 

quartz porphyry. The emeralds are present in two zones: in the northwestern zone (Riwat, Buzmal, 

Dahane Revat, and Darun) and in the southeastern zone (Khainch, Mikeni, and Darkhenj). The 

occurrences are associated with the contact between Silurian–lower Carboniferous carbonate rocks and 

upper Carboniferous–Permian flysch rocks. Along the contact, a series of closely spaced steep-dipping 

faults contain zones of fracturing, brecciation, boudinage, and cataclasis, as well as intensively 

hydrothermally altered rock. The beryllium mineralization with zones of emeralds is superimposed in a 

complex system of fractures upon hydrothermally altered (carbonate-sulfide) rocks (gabbro-diorites, 

marbles, and schists) especially near hydrothermally altered biotitized (phlogopitized) and chloritized 

diorite dikes (gabbro-diorites) (Samarin and Akkermantsev, written commun. to Afghan Ministry of 

Mining and Industries, 1977). 

Figure 13B–3. Elevations and topography of the Panjsher Valley area of interest. 
Chapter 13B. Analysis of Imaging Spectrometer Data for the Panjsher Valley Area of Interest 1023

Figure 13B–4. Geologic map of the Panjsher Valley area of interest from digital geologic map of Afghanistan 

(Doebrich and others, 2006; Abdullah and Chmyriov, 1977).

The Panjsher iron-ore district in the main valley of the Panjsher Valley AOI is a zone of 

imbricate structures and differently oriented fault blocks that are composed of Proterozoic and lower 

Paleozoic rocks near the Central Badakhshan fault. The known iron occurrences are siderite-hematite 

rocks. The siderite-hematite ores lie in extensive sheets and lenticular bodies enclosed in the Proterozoic 

carbonate strata. The essentially hematitic bodies assayed 60–65 weight-percent iron, with minor 

manganese, copper, lead, zinc, and silver, which occasionally forms economic concentrations. 

13B.4 Mineral Maps of the Panjsher Valley Area of Interest

Analysis of the HyMap imaging spectrometer data of the Panjsher Valley AOI using 

spectroscopic methods resulted in the identification of a wide variety of minerals exposed at the surface.

Although the occurrence of certain minerals may suggest that mineralization processes may have once 

operated in the area, many of the minerals that were identified are also common rock-forming minerals 

or minerals that can be derived from the weathering of a wide variety of rock types. Consequently, the 

distribution patterns of the identified minerals and the geologic context in which they occur are 

extremely important in understanding the origin of mapped mineral occurrences and evaluating the 

possible potential for related mineral deposits.

Figure 13B–6 depicts the results of the MICA analyses of the HyMap data for the Panjsher 

Valley AOI for the 2-μm materials including clays, carbonates, phyllosilicates, sulfates, altered 
1024 Summaries of Important Areas for Mineral Investment and Production Opportunities of Nonfuel Minerals in Afghanistan

minerals, and other materials. Carbonates and muscovite/illite cover most of the Panjsher Valley AOI. 

Chlorite/epidote is also found distributed in spatially contiguous areas. A zone with small groupings of 

pixels matched to dolomite and calcite+dolomite or serpentine spectra and to a lesser extent serpentine 

spectra runs parallel to the valley bottom on the south (300 to 900 m long parallel to the valley and 100 

to 500 m wide). At lower elevations, following the valley bottom, are groupings of 

dolomite+montmorillonite/calcite pixels. The serpentine class was mapped in spatially coherent patches 

dotting the AOI, with the larger patches north of the valley bottom. 

Figure 13B–5. Sites of known mineralization by deposit type (Peters and others, 2007) on the digital 

geologic map of the Panjsher Valley area of interest (Doebrich and others, 2006; Abdullah and 

Chmyriov, 1977). 
Chapter 13B. Analysis of Imaging Spectrometer Data for the Panjsher Valley Area of Interest 1025

Table 13B–1.

[Data are from 

Name

Known sites of mineralization in the Panjsher Valley area of interest. Peters and others (2007). Ag, silver; Cu, copper; Fe, iron; km, kilometers; m, meters; Zn, zinc]

Deposit type Major commodity Deposit size, description Alteration Mineralogy Gangue

Hes-i-Awal Unknown Cu Cu No data No data No data No data

Khainch Emerald Emerald Occurrence, width up to 3 km with extent of Biotitic alteration, albitization, Emerald, beryl, quartz, Biotite, albite, 

16 km carbonatization, tourmalinization, ankerite, calcite dolomite

pyritization, silicification

Mikeni Emerald Emerald Occurrence, width up to 3 km with extent of Biotitic alteration, albitization, Emerald, beryl, quartz, Biotite, albite, 

16 km carbonatization, tourmalinization, ankerite, calcite dolomite 

pyritization, silicification

Riwat Emerald Emerald Occurrence, width up to 3 km with extent of Emerald, beryl, quartz, Biotite, albite, 

16 km Biotitic alteration, albitization, ankerite, calcite dolomite

carbonatization, tourmalinization, 

pyritization, silicification

Buzmal Emerald Emerald Occurrence, width up to 3 km with extent of Emerald, beryl, quartz, Biotite, albite, 

16 km Biotitic alteration, albitization, ankerite, calcite dolomite

carbonatization, tourmalinization, 

pyritization, silicification

Dahane Revat Emerald Emerald Occurrence, width up to 3 km with extent of Emerald, beryl, quartz, Biotite, albite, 

16 km Biotitic alteration, albitization, ankerite, calcite dolomite

carbonatization, tourmalinization, 

pyritization, silicification

Darun Emerald Emerald Occurrence, width up to 3 km with extent of Biotitic alteration, albitization, Emerald, beryl, quartz, Biotite, albite, 

16 km, thickness of 0.1 to 10 m and more carbonatization, tourmalinization, ankerite, calcite dolomite, 

than 150 m down dip pyritization, silicification ankerite

Darkhenj Pegmatite Gem (emerald) No data No data No data No data

Bakhi Pegmatite Gem (emerald) No data No data No data No data

Butak Pegmatite Gem (emerald) No data No data No data No data

Manjyadar Pegmatite Muscovite Occurrence, thickness of 3 to 4 m with No data Muscovite Quartz, 

extent of 80 to 100 m oligoclase

Durnama Unknown Fe Fe Occurrence, thickness of 1 to 5 m and extent Marmorization Hematite No data

of 10 to 60 m

Panjsher Unknown Fe Fe Occurrence, thickness of 10 to 20 m with Marmorization Hematite No data

extent of 3 to 5 km

Nukra-Khana Unknown Fe Fe Occurrence, thickness of 2 to 10 m with Marmorization Hematite, siderite No data

extent from a few hundred meters up to 

few thousand meters

Hesa-i- Unknown Fe Fe No data No data No data No data

Bowum

Chukri-Naw Unknown Fe Fe, Ag Occurrence, thickness of 2 to 15 m with Marmorization Hematite, siderite No data

extent up to 1 km

Unnamed Polymetallic vein Zn Showing, total thickness of 380 m with Silicification, limonitization Pyrite, limonite Quartz

extent of a few hundred meters; thickness: 

2.5 to 3 m with extent of 110 to 115 m
1026 Summaries of Important Areas for Mineral Investment and Production Opportunities of Nonfuel Minerals in Afghanistan

Figure 13B–6. Map of carbonates, phyllosilicates, sulfates, altered minerals, and other materials derived from 

HyMap data in the Panjsher Valley area of interest. 

Large areas of the Panjsher Valley AOI had spectra that most closely matched the dry vegetation 

spectra in the reference spectral library. Closer examination of these areas revealed that the spectra of 

these pixels fell into two categories, those that had absorption features closely resembling the two 

primary lignocellulose features present in the spectra of dry vegetation (Kokaly and others, 2009) and 

those that appeared to have a mixture of mineral absorption features at 2.3 μm and dry vegetation 

absorption features. A false-color composite of three HyMap bands (red, green, and blue loaded with 

HyMap channels 111, 86, and 6, equivalent to 2.272, 1.738, and 0.542 μm, respectively) highlights the 

latter category with purple and blue tones (fig. 13B–7). It is possible that the spectral library does not 

have a representative entry for the mineral or mineral mixture of rocks in these areas. In general, the 

reflectance level in the longer wavelengths (2 to 2.5 μm) of rocks in these areas are low (12–19 percent 

at 2.272 μm) compared to surrounding areas (20–35 percent at 2.272 μm), which, in part, is why they 

appear blue in the false-color composite in figure 13B–7. The spectra in these areas have two absorption 

features at varying strength, one usually narrow and centered near 2.115 μm and the other typically 

broad and centered near 2.338 μm, which could arise solely from minerals or from a combination of 

minerals and overlying vegetation. Because of their proximity to the emerald occurrences, additional 

work to define the composition of rocks in these areas is warranted in conjunction with further analysis 

of the imaging spectrometer data.
Chapter 13B. Analysis of Imaging Spectrometer Data for the Panjsher Valley Area of Interest 1027

Figure 13B–7. False-color composite derived from HyMap data in the Panjsher Valley area of interest. Channels 

at 2.27, 1.73, and 0.54 μm were loaded into the red, green, and blue colors, respectively.

Figure 13B–8 shows the results for the iron-bearing (1 μm) minerals and other materials map.

One small concentration of hematite was found near the center of the AOI (lat 35.568289° N., long 

69.891194° E.). This is surrounded by a large area of pixels (more than 44 km2

) that were matched to 

fine- and medium-grained goethite and iron hydroxide. Large areas of goethite are also present along the 

southern edge of the Panjsher Valley AOI, with some jarosite present as well. A distinct area of Fe2+ and

Fe3+ type 2 pixels is mapped in the northern corner of the area. This material also is found at high 

elevations along the northern edge of the Panjsher Valley AOI.
1028 Summaries of Important Areas for Mineral Investment and Production Opportunities of Nonfuel Minerals in Afghanistan

Figure 13B–8. Map of iron-bearing minerals and other materials derived from HyMap data in the Panjsher Valley 

area of interest. 

Because of the large number of classes represented and the subtleties of the distribution patterns 

represented in these 1- and 2-μm maps, it is instructive to display these results as a series of image maps 

each depicting a selected group of minerals that are mineralogically related or commonly occur together 

in special geologic environments (figs. 13B–9 to 14). Figure 13B–9 shows the distribution of carbonate 

minerals in the Panjsher Valley AOI, whereas figure 13B–10 shows where clay minerals and micas 

occur. Because the micas cover a large portion of the AOI, more detailed discrimination of them into 

classes of muscovites and illite are depicted in figure 13B–11. The distribution of iron-oxide and ironhydroxide minerals are displayed in figure 13B–12. Minerals commonly found in hydrothermally altered 

rocks are mapped in figure 13B–13 and secondary minerals often associated with mineralized and (or) 

weathered rocks are mapped in figure 13B–14. Subsequent to a discussion of these maps, the minerals 

detected in the imaging spectrometer data around the emerald and iron-ore occurrences are presented in 

greater detail for two subareas, Emerald subarea and Silver-bearing iron-ore subarea, labeled on fig. 

13B–5. 
Chapter 13B. Analysis of Imaging Spectrometer Data for the Panjsher Valley Area of Interest 1029

Figure 13B–9. Distribution of carbonate minerals derived from HyMap data in the Panjsher Valley area of 

interest. 

13B.4.1 Carbonate Minerals

Carbonate minerals, mainly detected as calcite, were mapped over a large majority of the 

Panjsher Valley AOI (fig. 13B–9). In general, calcite was detected within every mapped rock unit. 

Dolomite mixed with calcite and (or) clay occurs over much less of the area, but in small, well-defined 

spatial patterns. Linear zones with small groupings of dolomite, and calcite+dolomite or serpentine, and 

serpentine classes (fig. 13B–6) occur parallel to the valley bottom (300 to 900 m long parallel to the 

valley and 100 to 500 m wide), within Silurian–Devonian and Ordovician rocks. The emeralds and 

pegmatites present in the southeastern zone (Khainch, Mikeni, Butak, and Darkhenj) are all located in 

close proximity to this linear trend. The carbonates detected in the imaging spectrometer data could be 

defining the contact between Silurian–lower Carboniferous carbonate rocks, and upper Carboniferous–

Permian flysch rocks associated with the emerald and pegmatite mineral occurrences. As the same 

minerals are mapped in linear features and patches in the vicinity of the northwestern emerald 

occurrences (Riwat, Buzmal, Dahane Revat, and Darun) and other locations in the Panjsher Valley AOI, 
1030 Summaries of Important Areas for Mineral Investment and Production Opportunities of Nonfuel Minerals in Afghanistan

additional spectroscopic analysis of the area is warranted to map the mineral composition of carbonates 

in greater detail and to better establish this association.

13B.4.2 Clays and Micas

Muscovite and illite concentrations were detected in all mapped rock units in the Panjsher Valley 

AOI (fig. 13B–10). In addition, the spectral signatures of chlorite and epidote were detected in cohesive 

patterns within most rock units, except for the Silurian–Devonian and Ordovician rocks in the southern 

portion of the area. Because muscovites were so widespread, the distinct muscovite spectra that were 

grouped in the 2-μm map were assigned more distinct colors and presented along with illite in a separate 

map (fig. 13B–11) that shows the distribution of pixels matching muscovites with variations in 

aluminum (Al) content. Separating the classes resulted in a map showing areas of distinct muscovite and 

illite composition in the Panjsher Valley AOI.

Figure 13B–10. Distribution of clay and mica minerals derived from HyMap data in the Panjsher Valley area of 

interest. 
Chapter 13B. Analysis of Imaging Spectrometer Data for the Panjsher Valley Area of Interest 1031

13B.4.3 Iron Oxides and Hydroxides

A small concentration of hematite was found near the center of the AOI (lat 35.568289° N., long 

69.891194° E.), surrounded by a large area of pixels (more than 44 km2) that were matched to fine- and 

medium-grained goethite (fig. 13B–12). Large areas of goethite are also present along the southern edge 

of the Panjsher Valley AOI, with some jarosite present as well. Jarosite was detected in association with 

goethite at high elevations in the eastern part of the AOI along the southern and northern edges. The 

iron-oxide and iron-hydroxide map identifies more pixels as containing jarosite than the 2-μm map 

(fig. 13B–6); jarosite in the iron map is detected using absorption features at wavelengths shorter than 

1.5 μm, whereas the jarosite in the 2-μm map is identified using a feature in the 2- to 2.5-μm wavelength 

region in addition to the shorter wavelength feature, making the jarosite in the 2-μm map a more 

conservative mapping of jarosite. Because of the extreme elevation changes in the area covered by the 

HyMap dataset, spectra at high elevations contain some residual atmospheric contamination. For these 

reasons, the identifications of jarosite should be examined in greater detail. 

Figure 13B–11. Distribution of muscovites and illites derived from HyMap data in the Panjsher Valley area of 

interest. 
1032 Summaries of Important Areas for Mineral Investment and Production Opportunities of Nonfuel Minerals in Afghanistan

13B.4.4 Common Alteration Minerals

Most of the minerals in this group are commonly present in hydrothermally altered rocks 

associated with epithermal mineral deposits (fig. 13B–13). Consequently, where they occur in distinct 

clusters is of great interest in terms of potential mineral deposits. However, the mineral distributions do 

not occur in distributions that are suggestive of such alteration in the Panjsher Valley AOI. 

13B.4.5 Common Secondary Minerals

Secondary minerals in the epidote and chlorite or epidote classes (fig. 13B–14) occur in most 

rock units of the Panjsher Valley AOI, though to a much less degree in the Silurian–Devonian and 

Ordovician polygons south of the valley bottom. The calcite+dolomite or serpentine class was mapped 

in spatially coherent patches dotting the AOI in the Silurian-Devonian and Ordovician rocks. The 

serpentine class was mapped in spatially coherent patches dotting the AOI, with the larger patches north 

of the valley bottom occurring in association with the tremolite or talc class. 

Figure 13B–12. Distribution of iron oxide and iron hydroxide derived from HyMap data in the Panjsher Valley 

area of interest. 
Chapter 13B. Analysis of Imaging Spectrometer Data for the Panjsher Valley Area of Interest 1033

Figure 13B–13. Distribution of common alteration minerals derived from HyMap data in the Panjsher Valley area 

of interest. 

13B.4.6 Emerald Subarea

Detailed maps of the Panjsher Valley AOI Emerald subarea are presented in figures 13B–15 to 

21 showing the contrast-enhanced natural color Landsat, geologic map with known mineral occurrences, 

2-μm minerals, 1-μm minerals, carbonate minerals, common secondary minerals, and the false-color 

composite derived from HyMap bands. A comparison of the Landsat and HyMap images (figs. 13B–15 

and 13B–21, respectively) shows a visual representation of the considerably greater detail in the HyMap 

data. Carbonate minerals, mainly detected as calcite, were mapped over a large majority of the Emerald 

subarea (fig. 13B–17). Linear zones with small groupings of dolomite, calcite+dolomite or serpentine, 

and serpentine classes occur (300 to 900 m long parallel to the valley and 100 to 500 m wide) within 

Silurian–Devonian and Ordovician rocks, stretching along a coherent trend greater than 16 km long in 

the southern portion of the subarea. The locations of emeralds and pegmatites in the southeastern zone 

(Khainch, Mikeni, Butak, and Darkhenj) are all located along this trend. The calcite and dolomite 
1034 Summaries of Important Areas for Mineral Investment and Production Opportunities of Nonfuel Minerals in Afghanistan

classes detected in the imaging spectrometer data could be defining the contact between Silurian–lower 

Carboniferous carbonate rocks and upper Carboniferous–Permian flysch rocks associated with the 

emerald and pegmatite mineral occurrences (fig. 13B–19). The dolomite and calcite+dolomite or 

serpentine classes (fig. 13B–19) and serpentine class (fig. 13B–20) are also mapped in patches in the 

vicinity of the northwestern emerald occurrences (Riwat, Buzmal, Dahane Revat, and Darun). There is 

no consistent relation between the mineral occurrences and the iron oxides and hydroxides 

(fig. 13B–18). The emeralds are described as occurring in intensively hydrothermally altered rock, with 

beryllium mineralization superimposed in a complex system of fractures upon hydrothermally altered 

(carbonate-sulfide) rocks (gabbro-diorites, marbles, and schists) especially near hydrothermally altered 

biotitized (phlogopitized) and chloritized diorite dikes (gabbro-diorites) (Samarin and Akkermantsev, 

written commun. to Afghan Ministry of Mining and Industries, 1977). Spectra of these types of rocks 

should be added to the entries in the spectral library used in this preliminary analysis (Kokaly, 2011) in 

subsequent analyses; this might allow the distribution of these altered rocks to be mapped. 

Figure 13B–14. Distribution of common secondary minerals derived from HyMap data in the Panjsher Valley 

area of interest. 
Chapter 13B. Analysis of Imaging Spectrometer Data for the Panjsher Valley Area of Interest 1035

Figure 13B–15. Contrast-enhanced Landsat Thematic Mapper natural-color image of the Emerald subarea of the 

Panjsher Valley area of interest. Geologic units and faults from (Doebrich and others, 2006; Abdullah and 

Chmyriov, 1977).

13B.4.7 Silver-Bearing Iron-Ore Subarea

Detailed maps of the Panjsher Valley AOI Silver-bearing iron-ore subarea are presented in 

figures 13B–22 to 24 showing the geologic map with known mineral occurrences, 1-μm minerals, and 

2-μm minerals, respectively. Five mineral occurrences have been found in the Early Proterozoic rocks in 

the area (fig. 13B–22). The descriptions of these mineral occurrences (Peters and others, 2007; Abdullah 

and others, 1977) mention hematite and siderite as associated mineralogy (table 13B–1). The known iron 

mineral occurrences are found within the area defined by the mapped goethite and iron hydroxide 

(fig. 13B–23). Only one small concentration of hematite is in the subarea (lat 35.568289° N., long 

69.891194° E.). This is surrounded by a large area of pixels (over 44 km2

) that were matched to fineand medium-grained goethite and iron hydroxide, which spans Silurian–Devonian and Early Proterozoic 

map units. The minerals detected in the 2-μm analysis of HyMap data reveal patterns of pixels with 

spectra matched to calcite, calcite+muscovite, and muscovite and kaolinite (fig. 13B–24). The 

uncertainty in the location of the silver-bearing iron-mineral occurrences may be preventing a clear link 

with the mineral distributions derived from the imaging spectrometer data. With the exception of the 
1036 Summaries of Important Areas for Mineral Investment and Production Opportunities of Nonfuel Minerals in Afghanistan

mapped hematite noted previously, siderite and hematite were not detected in the subarea; in contrast, 

goethite was the dominant iron-bearing mineral mapped in the region. Additional field sampling and 

geologic study of the subarea and (or) refinement of locations of the known mineral occurrences may 

allow association of the concentrations of pixels matched to kaolinite and muscovite, within the more 

generally calcite-dominated rocks, to the described setting of these mineral occurrences in lenticular 

bodies enclosed in the Proterozoic carbonate strata.

Figure 13B–16. Sites of known mineralization by deposit type (Peters and others, 2007) on the digital geologic 

map of the Emerald subarea of the Panjsher Valley area of interest (Doebrich and others, 2006; Abdullah and 

Chmyriov, 1977).
Chapter 13B. Analysis of Imaging Spectrometer Data for the Panjsher Valley Area of Interest 1037

Figure 13B–17. Map of carbonates, phyllosilicates, sulfates, altered minerals, and other materials derived from 

HyMap data in the Emerald subarea of the Panjsher Valley area of interest. 
1038 Summaries of Important Areas for Mineral Investment and Production Opportunities of Nonfuel Minerals in Afghanistan

Figure 13B–18. Map of iron-bearing minerals and other materials derived from HyMap data in the Emerald 

subarea of the Panjsher Valley area of interest. 
Chapter 13B. Analysis of Imaging Spectrometer Data for the Panjsher Valley Area of Interest 1039

Figure 13B–19. Map of carbonate minerals derived from HyMap data in the Emerald subarea of the Panjsher 

Valley area of interest. 
1040 Summaries of Important Areas for Mineral Investment and Production Opportunities of Nonfuel Minerals in Afghanistan

Figure 13B–20. Map of common secondary minerals derived from HyMap data in the Emerald subarea of the 

Panjsher Valley area of interest. 
Chapter 13B. Analysis of Imaging Spectrometer Data for the Panjsher Valley Area of Interest 1041

Figure 13B–21. False-color composite derived from HyMap data in the Emerald subarea of the Panjsher Valley 

area of interest. Channels at 2.27, 1.73, and 0.54 μm were loaded into the red, green, and blue colors, respectively.
1042 Summaries of Important Areas for Mineral Investment and Production Opportunities of Nonfuel Minerals in Afghanistan

Figure 13B–22. Sites of known mineralization by deposit type (Peters and others, 2007) on the digital geologic 

map of the Silver-bearing iron-ore subarea of the Panjsher Valley area of interest (Doebrich and others, 2006; 

Abdullah and Chmyriov, 1977).
Chapter 13B. Analysis of Imaging Spectrometer Data for the Panjsher Valley Area of Interest 1043

Figure 13B–23. Map of iron-bearing minerals and other materials derived from HyMap data in the Silver-bearing 

iron-ore subarea of the Panjsher Valley area of interest. 
1044 Summaries of Important Areas for Mineral Investment and Production Opportunities of Nonfuel Minerals in Afghanistan

Figure 13B–24. Map of carbonates, phyllosilicates, sulfates, altered minerals, and other materials derived from 

HyMap data in the Silver-bearing iron-ore subarea of the Panjsher Valley area of interest. 

13B.5 Summary 

Carbonates and muscovites cover most of the Panjsher Valley AOI. Chlorite/epidote is also 

found distributed in spatially contiguous areas. The serpentine class was mapped in spatially coherent 

patches dotting the AOI, with the larger patches north of the valley bottom. Linear zones with small 

groupings of dolomite, and calcite+dolomite or serpentine, and serpentine classes occur within Silurian–

Devonian and Ordovician rocks, stretching along a coherent trend (300 to 900 m long parallel to the 

valley and 100 to 500 m wide) greater than 16 km long in the southern portion of the subarea. The 

emeralds and pegmatites present in the southeastern zone are all located along this trend. A similar 

pattern of minerals detected in the imaging spectrometer data is also mapped in patches in the vicinity of 

the northwestern emerald occurrences. The calcite and dolomite classes detected in the imaging 

spectrometer data could be defining the contact between Silurian–lower Carboniferous carbonate rocks, 

and upper Carboniferous–Permian flysch rocks associated with the emerald and pegmatite mineral 

occurrences. Additional studies to examine the emerald occurrences in relation to these areas, in addition 

to spectra that do not match well to the reference entries in the spectral library used in this preliminary 

analysis, are warranted. A small concentration of hematite was found in the Panjsher Valley AOI 

(lat 35.568289° N., long 69.891194° E.). This is surrounded by a large area of pixels (over 44 km2

) that 

were matched to fine- and medium-grained goethite and iron hydroxide, which spans Silurian-Devonian 
Chapter 13B. Analysis of Imaging Spectrometer Data for the Panjsher Valley Area of Interest 1045

and Early Proterozoic map units. The known iron mineral occurrences are found within the area defined 

by the hematite, goethite, and iron hydroxide minerals detected in the imaging spectrometer data.

13B.6 References Cited

Abdullah, Sh., and Chmyriov, V.M., 1977, Geological map of Afghanistan: Kabul, Afghanistan, 

Ministry of Mining and Industry of the Democratic Republic of Afghanistan, scale 1:500,000.

Abdullah, Sh., Chmyriov, V.M., Stazhilo-Alekseev, K.F., Dronov, V.I., Gannan, P.J., Rossovskiy, L.N., 

Kafarskiy, A.Kh., and Malyarov, E.P., 1977, Mineral resources of Afghanistan (2d ed.): Kabul, 

Afghanistan, Republic of Afghanistan Geological and Mineral Survey, 419 p.

Bowersox, G.W., Snee, L.W., Foord, E.E., and Seal, R.R., II, 1991, Emeralds of the Panjshir Valley, 

Afghanistan: Gems and Gemology, v. 27, no. 1, p. 26–39.

Cocks, T., Jenssen, R., Stewart, A., Wilson, I., and Shields, T., 1998, The HyMap airborne hyperspectral 

sensor—The system, calibration and performance, in

Davis, P.A., 2007, Landsat ETM+ false-color image mosaics of Afghanistan: U.S. Geological Survey 

Open-File Report 2007–1029, 22 p. (Also available at 

Schaepman, M., Schlapfer, D., and Itten, K.I., 

eds., Proceedings of the 1st EARSeL Workshop on Imaging Spectroscopy, 6–8 October 1998, Zurich: 

Paris, European Association of Remote Sensing Laboratories, p. 37–43.

http://pubs.usgs.gov/of/2007/1029/

Doebrich, J.L., and Wahl, R.R., comps., with contributions by Doebrich, J.L., Wahl, R.R., Ludington, 

S.D., Chirico, P.G., Wandrey, C.J., Bohannon, R.G., Orris, G.J., Bliss, J.D., Wasy, Abdul, and 

Younusi, M.O., 2006, Geologic and mineral resource map of Afghanistan: U.S. Geological Survey 

Open File Report 2006–1038, scale 1:850,000, available at 

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Hoefen, T.M., Kokaly, R.F., and King, T.V.V., 2010, Calibration of HyMap data covering the country 

of Afghanistan,

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Conference, Alice Springs, Australia, September 12–17, 2010, p. 409, available at 

http://dl.dropbox.com/u/81114/15ARSPC-Proceedings.zip/.

Kazmi, A.H., and Snee, L.W., 1989, Emeralds of Pakistan, geology, gemology, and genesis: New York, 

VanNostrand Reinhold Co., and Karachi, Pakistan, Elite Publ., 269 p.

King, T.V.V., Kokaly, R.F., Hoefen, T.M., and Knepper, D.H., 2010, Resource mapping in Afghanistan 

using HyMap data, in Proceedings of the 15th Australasian Remote Sensing and Photogrammetry 

Conference, Alice Springs, Australia, September 12–17, 2010, p. 500, available at 

http://dl.dropbox.com/u/81114/15ARSPC-Proceedings.zip/

King, T.V.V., Kokaly, R.F., Hoefen, T.M., Dudek, K. and Livo, K.E., 2011, Surface materials map of 

Afghanistan—Iron-bearing minerals and other materials: U.S. Geological Survey Scientific 

Investigations Map 3152–B.

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Kokaly, R.F., King, T.V.V., and Livo, K.E., 2008, Airborne hyperspectral survey of Afghanistan 

2007—Flight line planning and HyMap data collection: U.S. Geological Survey Open-File Report 

2008–1235, 14 p.

Kokaly, R.F., Asner, G.P., Ollinger, S.V., Martin, M.E., and Wessman, C.A., 2009, Characterizing 

canopy biochemistry from imaging spectroscopy and its application to ecosystem studies: Remote 

Sensing of Environment, v. 113, p. 78–91.

Kokaly, Ray, 2011, PRISM—Processing routines in IDL for spectroscopic measurements: 

U.S. Geological Survey Open-File Report 2011–1155, available at http://pubs.usgs.gov/of/2011/1155/

Kokaly, R.F., King, T.V.V., Hoefen, T.M., Dudek, K. and Livo, K.E., 2011, Surface materials map of 

Afghanistan—Carbonates, phyllosilicates, sulfates, altered minerals, and other materials: U.S. 

Geological Survey Scientific Investigations Map 3152–A.

.

Peters, S.G., Ludington, S.D., Orris, G.J., Sutphin, D.M., Bliss, J.D., and Rytuba, J.J., eds., and the 

U.S. Geological Survey-Afghanistan Ministry of Mines Joint Mineral Resource Assessment Team, 

2007, Preliminary non-fuel mineral resource assessment of Afghanistan: U.S. Geological Survey 

Open-File Report 2007–1214, 810 p., 1 CD–ROM. (Also available at 

http://pubs.usgs.gov/of/2007/1214/.)