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that identify the physical conditions associated with mineralization (Adams, 1920;

Bodnar et al., 1985; Sander and Black, 1988; Dong et al., 1995; Simmons and

Christenson, 1994; Henley and Hughes, 2000). These various textures can be divided

into those that are produced during the original deposition of the phase, those that

represent recrystallization textures, and those that represent replacement of originally

precipitated material. Further, some of these textures are readily apparent in hand

samples, others require microscopic observation, with some are only revealed under

crossed-polars. Finally, some of these phases contain fluid inclusions that may be used to

infer the paleo-environment in the hydrothermal system, whereas others rarely contain

useful fluid inclusions. In this study, we have characterized the mineralogy and mineral

textures observable under the microscope, and these are summarized below.

The most common mineral texture observed in 752 out of 855 samples (Fig. 9)

from the Veta Madre is mosaic or jigsaw-textured quartz (Figs. 7A). This

recrystallization texture is characterized by aggregates of microcrystalline to crystalline

quartz crystals with interpenetrating grain boundaries (Dong et al., 1995) that is only

recognizable when observed under crossed polars (Fig. 8A, B). The texture is interpreted

to result from the recrystallization of massive chalcedony or amorphous silica (Dong et

al., 1995). In some cases the original colloform texture is readily apparent in plain

polarized light. As noted by Sander and Black (1988), primary fluid inclusions in this

type of quartz do not record the original depositional conditions. However, in this study

we observed many trails of secondary fluid inclusions in jigsaw quartz that record fluid

conditions in the Veta Madre after recrystallization of the original chalcedony or


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