辉石[Pyroxene] - 达人(其实～我是卧底，来自外星)

2005/11/17 | 辉石[Pyroxene]
类别(℃〖化学〗) | 评论(0) | 阅读(42) | 发表于 20:27: Minerals composed of single chains of silicate tetrahedra sharing corners. The repeat distance between silicate
tetrahedra facing the same direction is <IMG
WIDTH="41" HEIGHT="14" ALIGN="BOTTOM" BORDER="0"
SRC="http://scienceworld.wolfram.com/chemistry/pimg28.gif"> Å. In reality, the chain is twisted slightly in igneous and
metamorphic rocks. The general pyroxene formula is XYZ2O6, where X = Mg+2, Fe+2, Mn+2,
Li+, Ca+2, Na+, Y = Al+3, Fe+3, Cr+3, Cr+3, Ti+4, Mg+2, Fe+2,
Mn+2 Z = Si, Al+3, Fe+3 The most common form is (Ca,Mg,Fe)2Si2O6. On the basis of
their crystal system, pyroxenes are divided into triclinic clinopyroxenes (Cpx) and orthorhombic orthopyroxenes (Opx).
There are two types of sites in each variety: M1 and M2. Because of their structure, pyroxenes can be represented with
<a href="I-Beam.html">I-beam</a> figures. A diagnostic property for differentiating amphiboles (double-chain silicates) from pyroxenes is
that amphiboles cleave at<IMG
WIDTH="27" HEIGHT="15" ALIGN="BOTTOM" BORDER="0"
SRC="http://scienceworld.wolfram.com/chemistry/pimg29.gif">, while pyroxenes cleave at 93°.

<DIV ALIGN="CENTER">
<TABLE CELLPADDING=3 BORDER="1">
<TR><TD ALIGN="LEFT">Mineral</TD>
<TD ALIGN="LEFT">Formula</TD>
</TR>
<TR><TD ALIGN="LEFT">acmite</TD>
<TD ALIGN="LEFT">NaFeSi2O6</TD>
</TR>
<TR><TD ALIGN="LEFT">aegirine-augite</TD>
<TD ALIGN="LEFT">(Na2,Ca)(MgFe+2Fe+3)Si2O6</TD>
</TR>
<TR><TD ALIGN="LEFT">diopside</TD>
<TD ALIGN="LEFT">CaMgSi2O6</TD>
</TR>
<TR><TD ALIGN="LEFT">enstatite</TD>
<TD ALIGN="LEFT">MgSiO3</TD>
</TR>
<TR><TD ALIGN="LEFT">fassaite</TD>
<TD ALIGN="LEFT">Ca(MgAl)(AlSi)O6</TD>
</TR>
<TR><TD ALIGN="LEFT">jadeite</TD>
<TD ALIGN="LEFT">NaAlSi2O6</TD>
</TR>
<TR><TD ALIGN="LEFT">spodumene</TD>
<TD ALIGN="LEFT">LiAlSi2O6</TD>
</TR>
<TR><TD ALIGN="LEFT">Tschermak's pyroxene</TD>
<TD ALIGN="LEFT">CaAl(AlSi)O6</TD>
</TR>
<TR><TD ALIGN="LEFT">ureyite</TD>
<TD ALIGN="LEFT">NaCrSi2O6</TD>
</TR>
</TABLE>
</DIV>


<a href="Polymorph.html">Polymorphs</a> of pyroxene are given in the following table.
<DIV ALIGN="CENTER">
<TABLE CELLPADDING=3 BORDER="1">
<TR><TD ALIGN="LEFT">mineral</TD>
<TD ALIGN="LEFT">group</TD>
<TD ALIGN="LEFT">symmetry</TD>
<TD ALIGN="LEFT"><a href="I-Beam.html">I-beam</a></TD>
</TR>
<TR><TD ALIGN="LEFT">augite</TD>
<TD ALIGN="LEFT">clinopyroxene</TD>
<TD ALIGN="LEFT">C2/C</TD>
<TD ALIGN="LEFT">

<IMG
WIDTH="44" HEIGHT="45" ALIGN="BOTTOM" BORDER="0"
SRC="http://scienceworld.wolfram.com/chemistry/pimg31.gif"></TD> </TR>
<TR><TD ALIGN="LEFT">enstatite</TD>
<TD ALIGN="LEFT">orthopyroxene</TD>
<TD ALIGN="LEFT">Pbca</TD>
<TD ALIGN="LEFT">

<IMG
WIDTH="44" HEIGHT="45" ALIGN="BOTTOM" BORDER="0"
SRC="http://scienceworld.wolfram.com/chemistry/pimg32.gif"></TD> </TR>
<TR><TD ALIGN="LEFT">omphacite</TD>
<TD ALIGN="LEFT">clinopyroxene</TD>
<TD ALIGN="LEFT">P2/n</TD>
<TD ALIGN="LEFT"> </TD>
</TR>
<TR><TD ALIGN="LEFT">pigeonite</TD>
<TD ALIGN="LEFT">clinopyroxene</TD>
<TD ALIGN="LEFT">P21/C</TD>
<TD ALIGN="LEFT">

<IMG
WIDTH="44" HEIGHT="45" ALIGN="BOTTOM" BORDER="0"
SRC="http://scienceworld.wolfram.com/chemistry/pimg33.gif"></TD> </TR>
<TR><TD ALIGN="LEFT">protopyre</TD>
<TD ALIGN="LEFT">orthopyroxene</TD>
<TD ALIGN="LEFT">Pbcn</TD>
<TD ALIGN="LEFT">

<IMG
WIDTH="44" HEIGHT="45" ALIGN="BOTTOM" BORDER="0"
SRC="http://scienceworld.wolfram.com/chemistry/pimg32.gif"></TD> </TR>
<TR><TD ALIGN="LEFT">spodumene</TD>
<TD ALIGN="LEFT">clinopyroxene</TD>
<TD ALIGN="LEFT">C2</TD>
<TD ALIGN="LEFT"> </TD>
</TR>
</TABLE>
</DIV>; 0

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