Habit equant

MeliUte [Named from the Latin mel for honey and lithos, stone] (Ca,Na) (Mg,Fe,Al)[Si,OJ (Sorosilicates, pair) Tetragonal a s 780 pm c s 500 pm (Z = 2) Melilite type Uniaxial (+/-) = 1.638-1.657 03= 1.631-1.667 S= 0.010 5-5.5 2950 Habit equant or short prisnmtic crystals. Color colorless, yellow to light brown. Diaphaneity translucent. Luster vitreous. Streak white. Cleavage (001). Fracture conchoidal. Chemical gelatinizes in cold and dilute HCI. Occurrence ultramafic igneous rocks and skarns. 

Particle morphology refers to the external features or form of a powder s primary particles. This includes descriptions of shape, including aspect ratio, or crystal habit (plate, needle, lath, equant, etc.). Particles are not always observed as discrete entities. Rather, they are often associated with other particles, sometimes loosely held... 

The reasons for the equant sparry habit of cements in the meteoric realm are probably more debatable than the fact that these cements should be calcite. There are two principal models in the literature used to explain carbonate cement morphology these models are shown schematically in Figure 7.22. In the Folk (1974) model of Mg-poisoning, the Mg2+/Ca2+ ratio of the water plays an... 

The crystals of a given substance may vary in size, the relative development of the given faces and the number and kind of the faces (or forms) present that is, they may have different crystal habits. The habit describes the overall shape of the crystal in rather general terms and includes, for example, acicular (needle-like), prismatic, pyramidal, tabular, equant, columnar and lamellar types. Figure 1.7 shows the crystal habits of a hexagonal crystal. 

The particular shape of crystals as determined by the relative growth of their faces is called the crystal habit. Long thin crystals are called acicular (needle-like), whereas tabular crystals develop most rapidly in two dimensions. Equant crystals, on the other hand, develop pretty much equally in three directions. Figure 104 shows a schematic classification of these descriptions of habit. Of course, some crystals exist in easily recognized forms, such as the ones described in the previous section—cubic, octahedral, tetrahedral, etc. 

Group Equant or equiaxed crystal habits (i.e., form similarly developed in all three directions) Crystal habit Equiaxed Fluorite Granular Olivine ... 

Shortite [Named after the American mineralogist, Maxwell Naylor Short (1889-1952)1 (ICSD 16495 and PDF 21-1348) Na3Ca,(C03)3 M= 306.16 15.02 wt.%Na 26.18 wt.% Ca 11.77 wt.% C 47.03 wt.% 0 (Nitrates, carbonates, and borates) Orthorhombic a = 496.1 pm b = 1103 pm c= 712pm (Z = 2) P.G.mm2 S.G.Amm2 Biaxial a= 1.531 1.555 r= 1.570 27=75" 3 2600 (2610) Habit wedge-shaped, equant, or short prismatic crystals. Color colorless to pale yellow. Diaphaneity transparent. Luster vitreous. Streak n.a. Geavage (010). Fracture conchoidaL Decon oses in water releasing an insoluble residue of calcium carbonate. Fluorescent under UV radiation. Occurrence with calcite and pyrite. 

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