<div> こちらは2017年にアルジェリアのAdrarで発見されたNWA 13758の隕石です。 </div> <div> 隕石の種類はルムルチコンドライト（R3）です。詳細については以下の表のとおりです。 </div> <div> スライスされた標本ですので4.9cm×3.7cm×0.15cm，重量は7.28gとなります。 </div> <div> 写真の1枚目と2枚目はスキャナで撮ったものです。(白い糸状のものは，保管ケースのワタがスキャナに付いてしまったものです。暗色の隕石のため目立ってしまいました。) </div> <br> <table border="1" cellpadding="4" cellspacing="0"> <tbody> <tr valign="top"> <th colspan="2"><span>Northwest Africa 13758</span></th> </tr> <tr valign="top"> <td><big>Basic information</big></td> <td><span><b>Name:</b>&nbsp;Northwest Africa 13758</span><br><span>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;This is an OFFICIAL meteorite name.</span><br><span><b>Abbreviation:</b>&nbsp;NWA 13758</span><br><b>Observed fall:&nbsp;</b>No<br><b>Year found:&nbsp;</b>2017<br><b>Country:&nbsp;</b>Algeria<br><b><span>Mass:<a href="javascript:void(0);"><img src="https://www.lpi.usra.edu/meteor/qmark.gif" alt="help"></a></span></b>&nbsp;100 kg<br></td> </tr> <tr valign="top"> <td><big>Classification<br>&nbsp;&nbsp;history:</big></td> <td> <table border="0" cellspacing="0"> <tbody> <tr> <td><b>Recommended:&nbsp;&nbsp;</b></td> <td></td> <td></td> <td><b>R3</b>&nbsp;&nbsp;&nbsp;&nbsp;</td> </tr> </tbody> </table><br>This is 1 of 47 approved meteorites classified as R3.&nbsp;&nbsp;<br><br></td> </tr> <tr valign="top"> <td><big>Comments:</big></td> <td>Approved 8 Apr 2021</td> </tr> <tr valign="top"> <td><big><span>Writeup<a href="javascript:void(0);"><img src="https://www.lpi.usra.edu/meteor/qmark.gif" alt="help"></a></span></big></td> <td> <div> <big><u>Writeup from MB 110:</u></big> <br> <div> <div> <strong>Northwest Africa 13758</strong>&nbsp;(NWA 13758) </div> <div> Adrar, Algeria </div> <div> Purchased: 2017 </div> <div> Classification: Rumuruti chondrite (R3) </div> <div> <strong>History</strong>: A large group of identically appearing stones, found together, was purchased by a Saharan dealer from a nomad in Algeria and was subsequently acquired by Mark Lyon and Dustin Dickens. The original find was reportedly in the Tanezrouft Plateau, with the nearest town being Reggane, Algeria. </div> <div> <strong>Physical characteristics</strong>: Approximately 500 pieces ranging in mass from &lt;1 kg to &gt;5 kg, with a total known weight of approximately 100 kg. Dark brown sandblasted exterior. Saw cut reveals a breccia with fragments up to ~2 cm set in a fine-grained matrix. Abundant distinct chondrules are visible throughout. Two main lithologic domains exist within this meteorite, one has a gray, unstained matrix, and the second has a brownish-orange-stained matrix. </div> <div> <strong>Petrography</strong>: (C. Agee,&nbsp; <em>UNM</em>) Chondrite with mean apparent chondrule size 350±240 m (n=21) set in abundant matrix (~35 vol%). Electron microprobe analyses were performed separately on the two main lithologic domains. Domain "A" has compositionally unequilibrated olivine and pyroxene both in chondrules as well as single mineral fragments in the matrix. Very small grains of albitic plagioclase are present. Chromite, pentlandite, and troilite are ubiquitous. No metal or oxidized iron was detected. Domain "B" has compositionally unequilibrated olivine and pyroxene both in chondrules as well as single mineral fragments in the matrix. Domain "B" appears to have slightly more chondrules than domain "A". Very small grains of albitic plagioclase were present. Ti-rich chromite, pentlandite, and Ni-bearing troilite are ubiquitous. No metal or oxidized iron was detected. </div> <div> <strong>Geochemistry</strong>: (C. Agee,&nbsp; <em>UNM</em>) Domain "A": olivine Fa36.6±8.4, CV=23%, Fe/Mn=83±15, n=12; low-Ca pyroxene Fs21.4±6.8Wo0.9±0.5, Fe/Mn=39±19, n=4; augite Fs8.8±0.7Wo46.0±0.2, Fe/Mn=43±4, n=2; plagioclase An8.8±0.6Ab86.5±0.2Or4.7±0.7, n=3. Domain "B": olivine Fa38.7±5.8, CV=15%, Fe/Mn=87±10, n=12; low-Ca pyroxene Fs10.0±7.7Wo2.0±1.8, Fe/Mn=15±7, n=4; augite Fs11.4±0.9Wo44.8±1.3, Fe/Mn=51±11, n=2; plagioclase An9.2±0.9Ab85.9±1.6Or4.9±0.8, n=3. </div> <div> <strong>Classification</strong>: Rumuruti chondrite (R3). Domain "A" is approximately R3.7 and domain "B" is approximately R3.9, based on olivine coefficient of variation (CV) </div> <div> <strong>Specimens</strong>: 1127.72 g complete stone, and a 57.69 g full slice from a different complete stone, are on deposit at&nbsp; <em>UNM</em>. Mark Lyon holds the main mass including a total of 14 pieces weighing 19.84 kg, Dustin Dickens holds ~60 kg of medium to small stones. </div> </div> </div></td> </tr> <tr valign="top"> <td><big>Bibliography:</big></td> <td> <ul> <li>Bischoff, A. (2000) Mineralogical characterization of primitive, type-3 lithologies in Rumuruti chondrites.&nbsp;<i>Meteorit. Planet. Sci.</i>&nbsp;<b>35</b>&nbsp;699-706&nbsp;</li> </ul></td> </tr> <tr valign="top"> <td><big>Data from:<br>&nbsp;&nbsp;MB110<br>&nbsp;&nbsp;Table 0<br>&nbsp;&nbsp;Line 0:</big></td> <td> <table border="0"> <tbody> <tr valign="top"> <td><b>State/Prov/County:</b></td> <td>Adrar</td> </tr> <tr valign="top"> <td><b>Origin or pseudonym:</b></td> <td>Tanezrouft</td> </tr> <tr valign="top"> <td><b>Place of purchase:</b></td> <td>Algeria</td> </tr> <tr valign="top"> <td><b>Date:</b></td> <td>P 2017</td> </tr> <tr valign="top"> <td><b>Mass (g):</b></td> <td>100000</td> </tr> <tr valign="top"> <td><b>Pieces:</b></td> <td>500</td> </tr> <tr valign="top"> <td><b>Class:</b></td> <td>R3</td> </tr> <tr valign="top"> <td><b>Shock stage:</b></td> <td>S2</td> </tr> <tr valign="top"> <td><b>Weathering grade:</b></td> <td>W1</td> </tr> <tr valign="top"> <td><b>Fayalite (mol%):</b></td> <td>36.6±8.4, 38.7±5.8</td> </tr> <tr valign="top"> <td><b>Ferrosilite (mol%):</b></td> <td>21.4±6.8, 10.0±7.7</td> </tr> <tr valign="top"> <td><b>Wollastonite (mol%):</b></td> <td>0.9±0.5, 2.0±1.8</td> </tr> <tr valign="top"> <td><b>Classifier:</b></td> <td>C. Agee, UNM</td> </tr> <tr valign="top"> <td><b>Type spec mass (g):</b></td> <td>1185.41</td> </tr> <tr valign="top"> <td><b>Type spec location:</b></td> <td>UNM</td> </tr> <tr valign="top"> <td><b>Main mass:</b></td> <td>Mark Lyon</td> </tr> <tr valign="top"> <td><b>Comments:</b></td> <td>Submitted by C. Agee</td> </tr> </tbody> </table></td> </tr> </tbody> </table>