Dolomite Habits
Crystalline - Coarse - Occurs as
well-formed coarse sized crystals.
Massive - Uniformly indistinguishable
crystals forming large masses., Blocky - Rhombohedral - Crystal shape resemb les
rhomohedrons.
Associated Minerals include albite,
anatase, calcite, chlorite group,
fluorapatite, fluorite, galena,
gmelinite, marcasite, molybdenite,
pyrite, quartz, rutile, siderite and
sphalerite
Crystal habits include saddle shaped
rhombohedral twins and simple rhombs
some with slightly curved faces, also
prismatic, massive, granular and rock
forming. Streak is white.
The Dolomite Group of Minerals
The Dolomite Group is composed of
minerals with an unusual trigonal bar 3
symmetry. The general formula of this
group is AB(CO3)2, where A can be either
calcium, barium and/or strontium and the
B can be either iron, magnesium, zinc
and/or manganese.
The structure of the Dolomite Group is
taken from the Calcite Group structure.
The Calcite Group structure is layered
with alternating carbonate layers and
metal ion layers. The structure of the
Dolomite Group minerals is layered in
such a way that the A metal ions occupy
one layer which is followed by a
carbonate layer which is followed by the
B metal ion layer followed by another
carbonate (CO3) layer, etc. The layering
looks like this:
|A|CO3|B|CO3|A|CO3|B|CO3|A|... This
ordered layering of different or
nonequivalent ions causes a loss of the
two fold rotational axes and mirror
planes that are present in the Calcite
Group structure. Dolomite's symmetry
class is bar 3 whereas the Calcite
Group's symmetry class is bar 3 2/m. The
loss of symmetry allows only simple
crystal forms to be used by the Dolomite
Group minerals, mostly rhombohedrons.
Dolomite is a very common mineral and
ankerite is much more scarce. The other
members are considered rare to very
rare. The rarity of the members of this
group can be tied to the closeness in
radius of the A and B ions. In dolomite
the A and B ions are calcium and
magnesium which have the largest ionic
radius differential of the group
(approximately 33%). If the A and B ions
are close in radius, then they tend to
not segregate as easily into the
separate A and B layers, which is
required to form this structure and
therefore these minerals.
Recommended Filled of Application
Kind of powder |
Talc |
Mica |
Kaolin |
Red Iron oxide |
Fluorine |
Dolomite |
Calcite |
Bentonite |
Barite |
Ceramics |
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Chinaware |
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Excavation |
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Elecrode |
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Feed |
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Glass |
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Glaze |
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Glue |
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Gerannlation (p.v.c) |
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Insecticide |
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Isolation |
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lining |
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Paint |
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Pharmaceutical |
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Plastic |
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Rulp & paper |
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Rubber |
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Textile |
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