PDS_VERSION_ID        = PDS3
RECORD_TYPE           = STREAM

OBJECT                = TEXT
  PUBLICATION_DATE    = 2009-11-15
  NOTE                = "Sample description"
END_OBJECT            = TEXT
END

High-level Description: Nodular silicate-rich material coating the surface of
the Keanakakoi ash outcrop  (about 5 years old). Nodules created where acidic
water mixed in with magma dissolves SiO2. Water reaches the surface and
evaporates, leaving SiO2 (opal) and other evaporites.


Nodules are dark grey and flatish on top, paralleling the plane of the
surface, and are lighter in color and cauliflower-like in appearance on the
underside. Individual laminae of chemical precipitate are visible. Opal forms
flat, smooth, undulating disks that overlap like fish scales. Opal disks are
white on the edges and light grey in the middle, and the contact between the
grey and white is wavy. Edges of the disks curve under them. Surfaces that are
elevated have denser coating than inset surfaces.

Texture
  Grain morphology and appearance: Silicate-rich nodules (opal precipitate),
whitish-grey, some with a yellowish tinge (unconsolidated yellow fine grains
present as well). Nodules are composed of individual elongate crystals, giving
the nodules a spiney appearance. Opal occurs as small, round, vitreous
clusters found on both the substrate and other opal growths, thickest on edges
of substrate clasts. Coating tends to be concentrated on angular surfaces and
corners. of the dark, angular host rock.
  Grain size and sorting: Clusters are about 0.5-1 mm in diameter.
  Grain fabric:  Random orientation.

Sediment structure:  Parallel lamination.

Color: Dark grey grains coated with white/grey or slightly yellowish nodular
material.