Colloform

Pyrite is the most abundant ore mineral. It occurs as euhedral, framboidal, and colloform forms. Abundance of framboidal pyrite increases stratigraphically upwards. Colloform pyrite contains appreciable amounts of As and Cu (Nakata and Shikazono, unpublished), whereas these contents of euhedral and framboidal pyrite are less than the detection limit of an electron microprobe analyzer. Ishizuka and Imai (1998) found that the As content increases toward outer rim and reaches up to 5 wt% in the rim of colloform pyrite from the Fukazawa deposit. 

Present in euhedral to anhedral forms (E-A), colloform (Collo.), pelletal (Pell.), columnar (Col.), dendritic (Den.). 

Colloform textures of sulfide minerals were found in ores of the metamorphic grades lower than the green schist facies (Kase, 1988 Watanabe et al., 1993). These... 

Horikoshi, E. (1959) Colloform textures of cupriferous pyrite ores in the Okuki and Nebutoyama mines. Mining Geology, 9, 82-94 (in Japanese with English abst.). 

Yui, S. (1964) Colloform texture of a sulfide ore from the Kune mine, Shizuoka Prefecture (abst.). Mining Geology, 14, 60 (in Japanese). 

Colloform general term for botryoidal. mamillary, reniform with banded texture... 

Colloform texture the rounded, globular texture of a colloidal mineral deposit. 

Gayer, R., Rickard, D., 1994, Colloform Gold in Coal from Southern Wales Geology, v. 22, p. 35-38. 

T errazzo Framework of c. 60% quartz grains, with solution cavities, in a cryptocrystalline quartz or opaline matrix with colloform banding conchoidal fracture typical... 

Reniform or colloform Similar to mamillary intersecting kidney-shaped masses Hematite... 

Crystal morphology Equant, blocky, prismatic (large crystal faces) Colloform, (no crystal faces) Botryoidal ... 

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