3A) as scattered euhedral cubic-octahedral crystallites, framboid
aggregates or bundles (concretions) of framboidal aggregates.
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.
A range of stages of development of massive crystalline aggregates is observed in the samples: individual microcrysts, framboids
clusters, recrystallized megacryst overgrowths, and banded concentric zones.
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.
Pyrite and other sulfide minerals are often found in shales and carbonate bedrock as small (2-20 pm) framboids
(Schieber, 2011; Smedley & Kinniburgh, 2002, 2005).
Pyrite is common as crystals or small nodules, framboids
or replacement of macrofauna (mainly ammonites).
The presence of what appear to be degraded pyrite framboids
in the deeper horizons of both apicum soils (Fig.
A lump of biological indicators as algae, framboids
, disseminated pyrites, rhizolithes, rhizocretions, calcimicrobes, and filamentous bodies argue for deposition in reducing environment and extensive anoxia lead to biodegradation of organic matter.
During the late stationary growth phase or death phase, the gold NPs which were initially precipitated inside the cells were released into the bulk solution and formed suboctahedral to octahedral, subspherical to spherical aggregates resembling framboids
, and ultimately millimeter-thick gold foil at longer experimental duration [148,149].
Iron-oxide spherules are recovered from Agost section and are absent in Caravaca, where some scarce iron-oxide particulates or concretions occur but with no spherical shapes and in low quantities, mostly corresponding to altered pyrite 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