Veins range from less than 1 m to over 30 m in thickness and consist of quartz, chalcedony, calcite and pyrite, often showing banded, colloform
, crustiform, vuggy and/or brecciated textures.
The fine-grained layered and colloform
with synsedimentary features (Figure 4(b)).
Field evidence, ore microscopy, and electron microprobe analyses of the lodes suggest that the vein mineralization commenced with pre-ore precipitation of diagenetic marcasite, pyrite, and minor gel-like colloform
textured schalenblende and galena particularly in the vein--wall contacts (Akande and Mucke, 1993).
The outer margins may show colloform
bands of fine micritic zones with variation in color due to different grain size and iron content (Fig.
Trace and minor element variations and sulfur isotopes in crystalline and colloform
ZnS: Incorporation mechanisms and implications for their genesis.
banded quartz veining has also been observed.
The marcasite forms thick colloform
coatings of iridescent crystals on matrix pieces from thumbnail to large-cabinet size, and a fine miniature could be had for around $40.
The manganese mineralization occurs mainly as nodules within the sedimentary section, and both Mn and Fe minerals exhibit colloform
Three ore types are recognized texturally; (i) fine grained disseminated, (ii) coarse grained colloform
banded and (iii) complex fine and coarse replacive.
This mineral assemblage is found in hydrothermal breccia veins and exhibits colloform
textures consistent with low-sulphidation epithermal systems.
with a colloform
structure" (Frommurze et al., 1940).