Spherulite


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spherulite

[′sfir·ə‚līt]
(geology)
A spherical body or coarsely crystalline aggregate having a radial internal structure arranged about one or more centers.

Spherulite

 

a small sphere consisting of an aggregate of very fine acicular crystals radiating from a central point. Spherulites are found in magmatic and sedimentary rocks and vary in mineral composition and size. In magmatic rocks, spherulites are usually interpreted as endogenic contact formations in the marginal sections of diorites. In acidic lavas, they may occur through consolidation when the primary glassy mass cools; in basic lavas (variolites), such formations are called varióles. Spherulites also form in gas bubbles of already hardened rock during secondary precipitation of zeolites, quartz, and similar minerals; in such cases they may be called pseudospherulites. Carbonate, iron-manganese phosphate, chalcedonic, and other types of spherulites are found in sedimentary rocks. They usually result from the crystallization of material in colloidal nodules, and many are close in origin to concretions.

References in periodicals archive ?
Furthermore, the impacts of N5 concentration on the density of spherulite cores were investigated using TEM.
Through an optical microscope of polarized light, the structure of the spherical spherulite can be displayed and you can still see a pattern of the Maltese cross and concentric light and dark bands, which arise by rotation of the axes "b" and "c" around the axis "a" of unitary cell [63].
Spherulites acted as nucleation centers for the calcite crystals, which emerged from the spherulite nuclei as aggregates of isolated and small calcite crystals and progressively became larger and radially arranged, orienting parallel to each other and perpendicular to the external walls (Figs.
It was noted that surfaces were irregular, and contained a nonhomogeneous distribution of spherulites and the top and bottom of the samples were not uniform.
Thus, mixed GdCaHM crystal grows as single crystal with square platelet as well as spherulites.
The spherulite of PLLA/NA sample was observed using an XPN-203E (Changfang Optical instrument Co.
c] region, crystallized samples were characterized by a low crystalline degree with a small spherulite texture containing thin crystals.
The specially molecular structure of l,3:2,4-di(3,4-dimethylbenzylidene) sorbitol (DMDBS) made it able to self-assemble in the iPP melt and form fibrillar network [15-17], that can increase nucleating efficiency and decrease spherulite size.
In order to show the effect of the addition of PDLA on the isothermal crystallization behavior, the diameter of the PLLA spherulite against time is plotted in Figure 3.
In this way, the thickness of a spherulite was calculated from at least five different regions, and the average value was in the range of 5-10 [micro]m.
Unfortunately, the equation predicted spherulite size distributions, which deviated systematically from the experimentally observed distributions [15].
During crystal growth, polymer chains orient around the initial nucleation site, or nucleus, in a 3D pattern most often forming a spherical crystal cluster called a spherulite.