framboid

framboid

[′fram‚bȯid]
(geology)
A microscopic aggregate of pyrite grains, often occurring in spheroidal clusters.
References in periodicals archive ?
In modern euxenic environments the mean framboid diameters are generally smaller (below 10 [micro]m) and have a narrower size range than for oxic and dysoxic environments (Wilkin et al.
as pseudomorphs after framboids but mainly in voids or as hypocoatings and quasicoatings.
A range of stages of development of massive crystalline aggregates is observed in the samples: individual microcrysts, framboids, framboid clusters, recrystallized megacryst overgrowths, and banded concentric zones.
Thermal metamorphism led to recrystallisation and consolidation of original framboids into crystalline pyrite aggregates.
Within an individual framboid the size and habit of crystallites varied little; however, no consistent relationship between the size of framboids and individual crystals was evident.
The presence of what appear to be degraded pyrite framboids in the deeper horizons of both apicum soils (Fig.
Framboids are typically made of iron sulfides, but those riddling the fossils analyzed by Kaye's team--as well as Schweitzer's team in the T rex leg bone--were instead made of iron oxide.
Crystalline inclusions in leaf tissue: (0) absent; (1) sandy; (2) druses; (3) raphides, as well as other forms; (4) framboids.
Spot EDS analyses made with a SEM on pyrite framboids in core samples also suggest that most of the arsenic is associated with pyrite in soil materials (Angeloni 2003).
Earliest diagenesis in soils and the shallow subsurface generated: reworked mud aggregates; nodules of calcite, siderite, chert and phosphate; grains of Al-rich glaucony; and pyrite cubes and framboids.
3b) coated pyrite framboids and organic remnants, in-filling the organic remnants.
Iron monosulfides (FeS) are an important component in the cycling of iron and sulfur within acid sulfate soil (ASS) environments and occur either as coatings on pyrite framboids (Bush and Sullivan 1999) or as bottom sediments in drains and streams as the commonly known 'monosulfidic black oozes (MBOs)' (Sullivan et al.