Mangerite-charnockite
This specimen is typical of the metaigneous charnockitic rocks associated with the massif anorthosites in the Adirondacks. With variation in the quantity of modal quartz, the rock qualifies as either a charnockite or a mangerite. Quartz content is sufficiently variable to result in both rock types in a single outcrop. These rocks are part of the Mt. Arab complex (earlier referred to as the Tupper Lake Complex (Buddington 1939 p. 116)). The average modes of the mangerite (pyroxene syenite gneiss) and the associated charnockites are:<br /><table style="height:240px;"><tbody><tr><td>
<p>Â </p>
</td>
<td>
<p>Pyroxene syenite gneiss (1)</p>
</td>
<td>
<p>Charnockite (2)</p>
</td>
</tr><tr><td>
<p>Microperthite</p>
</td>
<td>
<p>46</p>
</td>
<td>
<p>46</p>
</td>
</tr><tr><td>
<p>Oligoclase</p>
</td>
<td>
<p>42</p>
</td>
<td>
<p>24</p>
</td>
</tr><tr><td>
<p>Quartz</p>
</td>
<td>
<p>3.3</p>
</td>
<td>
<p>16</p>
</td>
</tr><tr><td>
<p>Ferrohypersthene</p>
</td>
<td>
<p>2.0</p>
</td>
<td>
<p>6</p>
</td>
</tr><tr><td>
<p>Ferroaugite</p>
</td>
<td>
<p>3.6</p>
</td>
<td>
<p>1.4</p>
</td>
</tr><tr><td>
<p>Hornblende</p>
</td>
<td>
<p>1.8</p>
</td>
<td>
<p>2.8</p>
</td>
</tr><tr><td>
<p>Garnet</p>
</td>
<td>
<p>-</p>
</td>
<td>
<p>0.5</p>
</td>
</tr><tr><td>
<p>Â </p>
</td>
<td>
<p>Â </p>
</td>
<td>
<p>Â </p>
</td>
</tr><tr><td>
<p>(1)Â Â Â McLelland average of 5</p>
<p>(2)Â Â Â Analysis 112, Table 32, Buddington, 1939<br /><br /></p>
</td>
</tr></tbody></table>
Thin section shows K-feldspar, plagioclase and hypersthene.
1980
Western Minerals Inc.
AD-20
Fayalite-ferrohedenbergite-mesoperthite granite
This granite post-dates deformation and metamorphism. Silver got a U/Pb zircon age of 1125 Ma. This is a most unusual rock type. This rock has small quantities of fayalitic olivine and ferrohedenbergite that occur with mesoperthite and quartz. It also contains iron-rich orthopyroxene (Fe~90%).
Thin section shows feldspar with perthitic texture, quartz and olivine.
1980
Western Minerals Inc.
AD-21
Charnockite
This particular charnockite has been described, with analyses by deWaard and Romey, "Petrogenetic Relationships in the Anorthosite-Charnockite Series of the Snowy Mountain Dome," in Anorthosite Volume, New York State Museum Memoir 18, p.307-315. In this article, the authors show that a gradational contact exists between the anorthosite and surrounding charnockitic rocks. This is interpreted as the result of a comagmatic history for the rocks in question. The charnockites contain occasional xenocrysts of andesine which are believed to have been plucked off of the already solidified anorthosite by the still molten charnockite. Hills and Isachsen (1975) have dated these rocks at 1173±14 Ma.
Thin section shows K-feldspar, quartz and clinopyroxene.
1980
Western Minerals Inc.
AD-22
Woolen Mill gabbro
This specimen is representative of the pyroxene-plagioclase granulites that form from gabbros in the Adirondacks. This famous locality has been discussed, with analyses, by Buddington, 1939, Analysis 64L Table 15, and also in deWaard's 1965 type locality for the almandine-clinopyroxene subfacies of the granulite facies. The mineralogy is garnet-oligoclase-clinopyroxene-opaques. The texture is granoblastic. The original igneous texture and mineralogy have been totally replaced, at least locally, by two pyroxenes and plagioclase.
Thin section shows garnet, plagioclase and clinopyroxene.
1980
Western Minerals Inc.
AD-23
Wollastonite-garnet-diopside
This unique rock contains white crystalline wollastonite, brown grains of andradite garnet, and green diopside. Specimens courtesy of R.R. Bauer, plant manager of NYCO MInes (1980). McLelland reports some grossularite in addition to andradite.
The following information is from the original OCR document: This interesting rock is discussed by Buddington, 1939, p. 41-43. See also Buddington and Whitcomb, 1941, Geology of the Willsboro Quandrant, New York State Museum Bulletin 325 and Buddington, 1950, "Composition and Genesis of Pyroxene and Garnet Related to the Adirondack Anorthosite and Anorthosite-Marble Contacts," American Mineralogist, v.35, p.659-670.
1980
Western Minerals Inc.
AD-24