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A Photograph B Spectral cube with mineral C Representative spectra
indicators c) Calcite
1
Serpentine H2O 2
Tetr. Fe3+
Calcite C-O

1
eacRheflweacvtealnecnegtaht Calcite + 3
Reflectance (offset for clarity) serpentine

4 Serpentine

Fe2+ 4

Serpentine
2 with tetr. Fe3+

Tetrahedral OH Mg-OH Tetr.
Fe3+
Fe3+

1 cm 1 cm 3 0.5 1.0 1.5 2.0 2.5 0.5
Wavelength (μm)

Figure 2. Hyperspectral image of a serpentinite sample with red and green coatings (Nor4-14, described in Greenberger et al., 2015b)
from Norbestos, Quebec, Canada. (A) Photograph of the full rock. (B) Image showing spectral parameters that map calcite (red),
serpentine (green), and a feature at 0.45 µm (BD450; blue) due to tetrahedral Fe3+ within serpentine. The third dimension shows the
reflectance as a function of wavelength for each pixel within the image, with black and purple being low and red high. (C) Plot with
representative spectra of different units within the hyperspectral image. Colors correspond to colors in the spectral parameter image
with locations numbered. Close-up views of the 0.45 µm feature are shown on the right. These images were acquired with Headwall
Photonics Inc. High Efficiency Hyperspec® visible–near-infrared E-series (0.4–1.0 µm, 7 nm spectral resolution, 0.382 mrad
instantaneous field of view) and High Efficiency Hyperspec® shortwave infrared X-series pushbroom systems (1.0–2.5 µm, 12 nm
spectral resolution, 1.2 mrad instantaneous field of view) imaging spectrometers (see GSA Supplemental Data Repository [see footnote 1] for
more information).

Interior Amygdules Thick section C Thick section D OH Al- Fe/Mg-
Rind H2O OH OH
Datolite
A Near true color mineral indicator map B-OH

Datolite

Calcite Fe2+/Fe3+
charge
Calcic clinopyroxene transfer Exterior
and Fe/Mg clay
Reflectance (offset for clarity) Fe2+

B Mineral indicator map Transect
(far right)

Calcic clinopyroxene
and Fe/Mg-clay

Anhydrous
interior
matrix

3 mm

Fe3+

Anydrous Calcite Interior
interior
matrix 1 cm SWIR slope typical of rind
Calcite
GSA TODAY | DECEMBER 2015 Fe/Mg-clay 0.5 1.0 1.5 2.0 2.5
Wavelength (μm)

Figure 3. (A) Color composite image from a hyperspectral image acquired with the same imaging system used in Figure 2, approximating the true color of a pillow
lava cross section. (B) Mineral indicator map showing calcite in red, a spectral slope indicative of the rind in green, and Fe/Mg-clay in blue. The cyan box shows
the approximate location of the material on the adjacent cut face from which a thick section was prepared and imaged. (C) Mineral indicator and spectral
parameter image of the thick section using the same parameters as (B). The dashed white outline shows the location of identified datolite. (D) Plot with spectral
transect from the interior through the alteration rind (purple to green; location of transect shown in A). The spectrum of the innermost point (purple) reflects
the oxidized, anhydrous nature of the interior matrix. Spectra of the rind (green) are consistent with an Fe/Mg-clay (chlorite and/or nontronite) and calcic
clinopyroxenes. Guidelines show absorption features due to various molecular vibrations or other key spectral characteristics. A scaled, three-point moving
average spectrum of datolite (black) acquired within the thick section is also shown. This figure is modified from data presented in Greenberger et al. (2015a).

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