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Figure 28:
A. Cluster of two (or more) phenocrysts of pyroxene in sample with porphyritic texture. The
pyroxene is green and weakly pleochroic. It contains inclusions of magnetite (black). The field
of view is about 3.9 x 5.3 mm. Plane-polar light. DDH 172-221.5
B. Same pyroxenes shown in A. Crossed-polar light. Shows typical interference colors of the
pyroxenes in the rocks of the Ok Tedi Intrusive Complex. The field of view is about 3.9 x 5.3
mm. Crossed-polar light. DDH 172-221.5
C. Crystals of pyroxene in a rock with phaneritic texture. Two directions of cleavage can be
seen in the equant crystals northwest of the large crystal in the lower left part of the photograph.
These cleavages cross at nearly right angles. A stubby crystal of apatite abuts against the lower
edge of the large pyroxene in the center of the photograph. Crystals of magnetite abut against, or
are included within the pyroxenes. The field of view is about 3.0 x 4.2 mm. Plane-polar light.
DDH 74-66
D. Common association of magmatic minerals in a sample of phanerite. Several pyroxenes,
including the large central crystal, in juxtaposition with magnetite and feldspar. A single
diamond shape crystal of sphene can be seen in the lower center of the photograph. The field of
view is about 4 x 6 mm. Plane-polar light. DDH 342-84.5.
E. Eight-sided cross-section through a crystal of pyroxene in a sample of porphyry. The crystal
shows the typical cleavage (~87) of pyroxene and contains two inclusions of magnetite (black).
The field of view is about 0.6 x 0.9 mm. Plane-polar light. DDH 172-221.5
F. Same crystal of pyroxene seen in E. Crossed-polar light. DDH 172-221.5
G. Photomicrograph showing the typical spatial distribution and abundance (~13%) of pyroxene
in the least-altered phanerites of the Ok Tedi Intrusive Complex. Also shows the typical close
spatial proximity of magnetite and pyroxene. The field of view is about 4.1 x 6.2 mm.
Plane-polar light. Ok Tedi 1009.
H.Photomicrograph showing the typical spatial distribution and abundance (~13%) of pyroxene in the least-altered phanerites of the Ok Tedi Intrusive Complex. Also shows the typical close spatial proximity of magnetite and pyroxene. The field of view is about 4 x 6 mm. Plane-polar light. Ok Tedi 1009.
