Sperrylite

<h2 id="geologic-occurrence">Geologic occurrence</h2>
<p>Sperrylite is the most common platinum mineral, it generally occurs with a wide array of other unusual minerals, including <a href="/facts/Cooperite_(mineral)/ErvFDce0">cooperite</a> [(Pt,Pd,Ni)S], <a href="/facts/Laurite/b7vljzAt">laurite</a> [RuS2], kotulskite [Pd(Te,Bi)], <a href="/facts/Merenskyite/L3PYkCQX">merenskyite</a> [(Pd,Pt)(Te,Bi)2], iridium-osmium (Ir-Os) <a href="/facts/Alloy/I7w7WQWR">alloys</a>, sudburyite [(Pd,Ni)Sb], omeiite [(Os,Ru)As2], testibiopalladite [PdTe(Sb,Te)], and niggliite [PtSn], to name a few. It does not readily decompose through normal <a href="/facts/Weathering/uSYGlv0H">weathering</a> processes and, consequently, has been reported in widely scattered <a href="/facts/Alluvial_deposits/Bo78QRlp">alluvial deposits</a>.
</p><p>It was first found as tiny crystals found with <a href="/facts/Rhodolite/YhRcVT3r">rhodolite</a> <a href="/facts/Garnet/kqh2lWQI">garnet</a> and <a href="/facts/Corundum/B7RRbcaE">corundum</a> during alluvial <a href="/facts/Gemstone/kHffmvE3">gem</a> mining in streams draining Mason Mountain, <a href="/facts/Macon_County,_North_Carolina/fFJwb0GF">Macon County, North Carolina</a> (Hidden 1898). Sperrylite has been identified in <a href="/facts/Finland/G5Ak6T91">Finland</a> from sulfide deposits generally associated with layered mafic-ultramafic complexes.
</p>
<h2 id="structure">Structure</h2>
<p>Sperrylite belongs to the pyrite group of minerals and therefore it shares similar structure and crystal habits with them. Analyses typically show minor amounts of rhodium. Trace copper, iron, and antimony as well as intergrowths with Pt-Fe are reported from some occurrences. Sperrylite crystallizes in Pa3, with a =5.9681(l) A. (Szymański, 1979). It has very similar crystal structure as in platarsite (ideally PtAsS).  Sperrylite crystals vary considerably in shape and size and are usually enclosed in a variety of host minerals. They are usually closely associated with basemetal sulfide. They are commonly at the edge and partially enclosed by pentlandite, pyrrhotite or chalcopyrite. Seabrook (2004).
</p><p>Sperrylite is composed of loose <a href="/facts/Aggregate_(geology)/m7KAYtau">aggregate</a> of bright silver cubes, some with octahedral modifications. The grains are mostly anhedral, but a few euhedral grains could also be encountered. Sperrylite is formed by <a href="/facts/Contact_metamorphism/8eWHgy6K">contact metamorphism</a>, as in indicated by the development of <a href="/facts/Triple_point/Npary634">triple point</a> annealing contacts with <a href="/facts/Pyrrhotite/gTgn4Mmf">pyrrhotite</a> grains. The grains of sperrylite are surrounded by later veins of pyrite.
</p><p>Sperrylite is cubic (2/m3) and is typically seen in well-developed cubes or cuboctahedra, some of which are so highly modified that crystal edges and corners appear rounded. (Nicol and Goldschmidt 1903) identified seventeen crystal forms exhibited by sperrylite, including four different trapezohedra, a trisoctahedron, five pyritohedra, and four diploids. Crystals to 2.5 cm have been reported.
</p>
<table><tbody><tr><td>Cell dimensions</td><td>a = 5.967, Z = 4; V = 212.46 Den(Calc)= 10.78</td></tr><tr><td>Crystal system</td><td>Isometric – Diploidal H-M Symbol (2/m 3) Space Group: P a3</td></tr><tr><td>X ray diffraction</td><td>By Intensity(I/Io): 1.801(1), 1.148(0.7), 2.98(0.6)</td></tr><tr><td>Forms</td><td>[1 0 2] [1 1 1] [1 0 0]</td></tr></tbody></table>
<h2 id="physical-properties">Physical properties</h2>
<p>Sperrylite is a tin-white mineral known for its brilliant metallic luster, with a grey to black streak. It has indistinct cleavage on {001} and a conchoidal fracture and is brittle. Its hardness is between 6 and 7, and it is quite dense with a calculated specific gravity of 10.78. It has an isometric crystal structure, conchoidal fracture, is non-magnetic and non-radioactive.
</p>
<h2 id="discovery">Discovery</h2>
<p>Sperrylite was first described by H. H. Wells in 1889 from material collected at the Vermilion mine in what is now the <a href="/facts/Sudbury_District,_Ontario/9joWFV5A">Sudbury district</a>, <a href="/facts/Ontario,_Canada/HUkxk5Rf">Ontario, Canada</a>. He named it for Francis L. Sperry, chief chemist with the <a href="/facts/Canadian_Copper_Company/yRqLwkL9">Canadian Copper Company</a> of Sudbury, who collected the original material in 1887 (Mitchell 1985). It occurred in weathered material with colorless transparent <a href="/facts/Cassiterite/d4hzR7LB">cassiterite</a> [SnO2], which is thought to have been derived from the oxidation of <a href="/facts/Stannite/omKID2Cy">stannite</a> [Cu2(Fe,Zn)SnS4].
</p>
<h2 id="see-also">See also</h2>
<ul><li><a href="/facts/List_of_minerals/4rMMcv2D">List of minerals</a></li>
<li><a href="/facts/List_of_minerals_named_after_people/ElPKA5lI">List of minerals named after people</a></li></ul>

Look up <i>sperrylite</i> in Wiktionary, the free dictionary.

Wikimedia Commons has media related to Sperrylite.

<ul><li>Cook, Robert B. (2001) Connoisseur's choice; sperrylite, Talnakh, Noril'sk District, Siberia, Russia. Rocks and Minerals, 0035-7529, Vol. 76, Issue 1</li>
<li>Szymański, J.T. (1979) the crystal structure of platarsite, Pt (As, S) 2, and a comparison with sperrylite, PtAs2. Canadian Mineralogist: 17: 117–123.</li>
<li>Hidden, W. E. 1898. Occurrence of sperrylite in North Carolina. American Journal of Science 6:381</li>
<li>Mitchell, R. S. 1985. Who's who in mineral names: Willard Lincoln Roberts and Francis Lewis Sperry. Rocks & Minerals 60:26–28.</li>
<li>Wells, H. H. 1889. Sperrylite, a new mineral. American Journal of Science, vol 37, pp 67–70</li>
<li>Seabrooke, C.L. 2004. Platinum-group minerals in the Raglan Ni-Cu-(PGE) sulfide deposit, Cape Smith, Quebec, Canada. Canadian mineralogist. Vol. 42, Part 2, pp. 485–497</li>
<li>Gait, R. I. 1982. Sperrylite from the type locality. Mineralogical Record 13:159-60</li>
<li>Penfield, S. L. 1889. On the Crystalline form of Sperrylite. American Journal of Science. Vol. 37, pp. 71–73</li>
<li>Goldschmidt, V. 1903. New forms of Sperrylite. American Journal of Science, Vol. 15, pp. 450–458</li></ul>

<h2 id="references">References</h2>

<ol>
<li id="fn:1"><p>Thompson, John Fairfield; Beasley, Norman (1960). For the Years to Come: A Story of International Nickel of Canada. Toronto: Longmans, Green & Co. <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li>
</ol>

Sperrylite open-in-new

Sperrylite