<TABLE BORDER=0 TITLE="Unconventional Lapidarist" SUMMARY="Unconventional Lapidarist"> <TR> <TD><A HREF="http://www.unconventionallapidarist.com" TITLE="Unconventional Lapidarist"><IMG SRC="https://store.nexternal.com/lapidarist/lapidarist-logo-small.jpg" ALT="Unconventional Lapidarist" NAME="Unconventional Lapidarist" BORDER=0></A></TD> <TD>&nbsp;&nbsp;</TD> <TD><H1><A HREF=http://store.unconventionallapidarist.com/Category667>Designer Cabochons</A> / Psilomelane</H1></TD> </TR> </TABLE> <P><b>Psilomelane</b>, also known as <b>black hematite</b>, is a group name for hard black manganese oxides such as hollandite and <span class="mw-redirect">romanechite</span>. Psilomelane consists of hydrous manganese oxide with variable amounts of barium and potassium.<eol><eol><eol><eol><eol><eol><eol><eol><eol><br /><br /></eol></eol></eol></eol></eol></eol></eol></eol></eol><h2><span class="mw-headline">Formula</span></h2> <p>Generalized formula may be represented as Ba(Mn<sup>2+</sup>)(Mn<sup>4+</sup>)<sub>8</sub>O<sub>16</sub>(OH)<sub>4</sub> or as (Ba,H<sub>2</sub>O)<sub>2</sub>Mn<sub>5</sub>O<sub>10</sub>. It is sometimes considered to be a hydrous manganese manganate, but of doubtful composition. The amount of manganese present corresponds to 70-80% of manganous oxide with 10-15% of available <a href="http://en.wikipedia.org/wiki/Oxygen" title="Oxygen">oxygen</a>.</p> <p><a name="Characteristics" id="Characteristics"></a></p> <h2><span class="editsection"></span> <span class="mw-headline">Characteristics</span></h2> <p>Psilomelane is amorphous and occurs as botryoidal and stalactitic masses with a smooth shining surface and submetallic lustre. The mineral is readily distinguished from other hydrous manganese oxides (manganite and wad) by its greater hardness 5 to 6; the specific gravity varies from 3.7 to 4.7. The streak is brownish black and the fracture smooth. Owing to its <span class="mw-redirect">amorphous</span> nature, the mineral often contains admixed impurities, such as <span class="mw-redirect">iron hydroxides</span>. It is soluble in hydrochloric acid with evolution of chlorine gas.</p> <font class="font2">This article is licensed under the <a target="_blank" rel="nofollow" title="http://www.gnu.org/copyleft/fdl.html" class="external text" href="http://www.gnu.org/copyleft/fdl.html">GNU Free Documentation License</a>. It uses material from the <a target="_blank" rel="nofollow" title="http://en.wikipedia.org/wiki/Psilomelane" class="external text" href="http://en.wikipedia.org/wiki/Psilomelane">Wikipedia article "Psilomelane"</a></font> </P> <BR clear=left><BR><P><A HREF=http://store.unconventionallapidarist.com/Product19971 TITLE="Psilomelane Designer Cabochons"><IMG SRC="https://store.nexternal.com/lapidarist/images/t_psilcabs1021.jpg" ALIGN=left ALT="Psilomelane Designer Cabochons" NAME="Psilomelane Designer Cabochons" BORDER=0></A> <A HREF=http://store.unconventionallapidarist.com/Product19971 TITLE="Psilomelane Designer Cabochons">Psilomelane Designer Cabochons</A> -- <STRIKE>$80.00</STRIKE> <font color=black><B>$56.00</B></font> -- Psilomelane Designer Cabochons ( 36.1mm x 25.1mm x 6.3mm )</P> <BR clear=left><BR><P><A HREF=http://store.unconventionallapidarist.com/Product19972 TITLE="Psilomelane Designer Cabochons"><IMG SRC="https://store.nexternal.com/lapidarist/images/t_psilcabs1022.jpg" ALIGN=left ALT="Psilomelane Designer Cabochons" NAME="Psilomelane Designer Cabochons" BORDER=0></A> <A HREF=http://store.unconventionallapidarist.com/Product19972 TITLE="Psilomelane Designer Cabochons">Psilomelane Designer Cabochons</A> -- <STRIKE>$80.00</STRIKE> <font color=black><B>$56.00</B></font> -- Psilomelane Designer Cabochons ( 39.2mm x 24.8mm x 5.9mm )</P> <BR clear=left><BR><P><A HREF=http://store.unconventionallapidarist.com/Product19973 TITLE="Psilomelane Designer Cabochons"><IMG SRC="https://store.nexternal.com/lapidarist/images/t_psilcabs1023.jpg" ALIGN=left ALT="Psilomelane Designer Cabochons" NAME="Psilomelane Designer Cabochons" BORDER=0></A> <A HREF=http://store.unconventionallapidarist.com/Product19973 TITLE="Psilomelane Designer Cabochons">Psilomelane Designer Cabochons</A> -- <STRIKE>$80.00</STRIKE> <font color=black><B>$56.00</B></font> -- Psilomelane Designer Cabochons ( 35.8mm x 23.8mm x 7.7mm )</P> <BR clear=left><BR><P><A 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<STRIKE>$80.00</STRIKE> <font color=black><B>$56.00</B></font> -- Psilomelane Designer Cabochons ( 30.6mm x 22.5mm x 8.5mm )</P> <BR clear=left><BR><P><A HREF=http://store.unconventionallapidarist.com/Product19976 TITLE="Psilomelane Designer Cabochons"><IMG SRC="https://store.nexternal.com/lapidarist/images/t_psilcabs1026.jpg" ALIGN=left ALT="Psilomelane Designer Cabochons" NAME="Psilomelane Designer Cabochons" BORDER=0></A> <A HREF=http://store.unconventionallapidarist.com/Product19976 TITLE="Psilomelane Designer Cabochons">Psilomelane Designer Cabochons</A> -- <STRIKE>$60.00</STRIKE> <font color=black><B>$42.00</B></font> -- Psilomelane Designer Cabochons ( 29.1mm x 20.3mm x 7.7mm )</P> <BR clear=left><BR><P><A HREF=http://store.unconventionallapidarist.com/Product19977 TITLE="Psilomelane Designer Cabochons"><IMG SRC="https://store.nexternal.com/lapidarist/images/t_psilcabs1027.jpg" ALIGN=left ALT="Psilomelane Designer Cabochons" NAME="Psilomelane Designer Cabochons" BORDER=0></A> <A HREF=http://store.unconventionallapidarist.com/Product19977 TITLE="Psilomelane Designer Cabochons">Psilomelane Designer Cabochons</A> -- <STRIKE>$50.00</STRIKE> <font color=black><B>$35.00</B></font> -- Psilomelane Designer Cabochons ( 40.1mm x 21.2mm x 6.8mm )</P> <BR clear=left><BR><P><A HREF=http://store.unconventionallapidarist.com/Product19980 TITLE="Psilomelane Designer Cabochons"><IMG SRC="https://store.nexternal.com/lapidarist/images/t_psilcabs1030.jpg" ALIGN=left ALT="Psilomelane Designer Cabochons" NAME="Psilomelane Designer Cabochons" BORDER=0></A> <A HREF=http://store.unconventionallapidarist.com/Product19980 TITLE="Psilomelane Designer Cabochons">Psilomelane Designer Cabochons</A> -- <STRIKE>$80.00</STRIKE> <font color=black><B>$56.00</B></font> -- Psilomelane Designer Cabochons ( 34.9mm x 19.2mm x 9mm )</P> <BR clear=left><BR><P><A HREF=http://store.unconventionallapidarist.com/Product19981 TITLE="Psilomelane Designer Cabochons"><IMG 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