plagioclase – מילון אנגלי-אנגלי

מילים נרדפות: felspar, feldspar

English Wikipedia - The Free Encyclopedia

Plagioclase

Plagioclase is a series of tectosilicate minerals within the feldspar family. Rather than referring to a particular mineral with a specific chemical composition, plagioclase is a solid solution series, more properly known as the plagioclase feldspar series (from the Greek "oblique fracture", in reference to its two cleavage angles). This was first shown by the German mineralogist Johann Friedrich Christian Hessel (1796–1872) in 1826. The series ranges from albite to anorthite endmembers (with respective compositions NaAlSi₃O₈ to CaAl₂Si₂O₈), where sodium and calcium atoms can substitute for each other in the mineral's crystal lattice structure. Plagioclase in hand samples is often identified by its polysynthetic crystal twinning or 'record-groove' effect.

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WordNet 2.0

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plagioclase

Noun
1. any of a rock-forming series of triclinic feldspars
(synonym) oligoclase
(hypernym) feldspar, felspar
(hyponym) albite, white feldspar
(substance-holonym) basalt

Babylon French-English

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plagioclase

nm. plagioclase, mineral of the feldspar group

Webster's Revised Unabridged Dictionary (1913)

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Plagioclase

(n.)
A general term used of any triclinic feldspar. See the Note under Feldspar.

Webster's Revised Unabridged Dictionary (1913), edited by Noah Porter. About

Mineralogy Database

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Plagioclase

General Information:

Chemical Formula:
(Na,Ca)(Si,Al)4O8

Composition:
(Molecular Weight = 270.77 gm)
Sodium 4.25 % Na
Calcium 7.40 % Ca
Aluminum 9.96 % Al
Silicon 31.12 % Si
Oxygen 47.27 % O

Empirical Formula:
Na0.5Ca0.5Si3AlO8

Environment:
Igneous and metamorphic rocks.

IMA Status:
Not IMA Approved

Locality:
Common world wide occurrences.

Name Origin:
From the Greek plagios - "oblique" and klao - "I cleave" in allusion to the obtuse cleavage angles of the good cleavages.
Physical Properties:

Cleavage:
[001] Good, [010] Good

Color:
white, gray, bluish white, reddish white, or greenish white.

Density:
2.61 - 2.76, Average = 2.68

Diaphaniety:
Transparent to translucent

Habits:
Massive - Granular - Common texture observed in granite and other igneous rock., ,

Hardness:
6-6.5 - Orthoclase-Pyrite

Luminescence:
Non-fluorescent.

Luster:
Vitreous (Glassy)

Streak:
white
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plagioclase – מילון אנגלי-עברי

plagioclase – מילון אנגלי-אנגלי