CHAPTER X. 
DESCRIPTION OF THE COLLECTION. 
GRANITIC AND METAMORPHIC ROCKS.—VOLCANIC ROCKS.—TRAP FROM DYKES NEAR GALISTEO.—LAVA FROM SAN FRANCISCO 
MOUNTAIN.—STRATIFIED ROCKS AND GYPSUM.—LIMESTONE OF DELAWARE MOUNTAIN.—MAGNESIAN LIMESTONE OF THE LLANO 
ESTACADO.—GYPSUM AND SELENITE.—SANDSTONE FROM THE CAJON PASS.—MISCELLANEOUS SPECIMENS.—ORES AND MINERALS.— 
COPPER ORE.—GoOLD.—IRON ORE.—HEMATITE.— ABSENCE OF MAGNETITE.—COAL.—SIGILLARIA.—LEPIDODENDRON. 
GRANITIC AND METAMORPHIC. 
[No. 1 to No. 38.] 
Nos. 1 and 2. Cañon de Tejeras, near Albuquerque.—These two specimens, as the labels 
indicate, appear to be from the same locality. They are also alike in their mineral character. 
The granite may be said to be coarse-grained, and contains a large amount of black or dark 
green mica, in masses from one-sixteenth to one-quarter of an inch in diameter. I have not 
detected any hornblende in the specimens. 
No. 3. Pueblo creek.—This specimen is a compact, fine-grained granite, of a delicate lilac 
color, modified by the grains of dark-colored mica. It is slightly porphyritic, containing several 
small isolated crystals of feldspar. The pink or lilac color appears to be due partly to the 
quartz, which is purplish or amethystine. This rock will furnish excellent building material. 
No. 4. Between Pueblo creek and Turkey creek.—This specimen is a large mass of amorphous 
quartz, stained with oxide of iron, and bounded on two sides by implanted crystals of a beauti- 
ful white silvery mica. The specimen appears to be a part of a vein which probably traversed 
a granitic rock. A small cavity in one end of the quartz is cellular, and appears to have been 
filled with iron pyrites, which has probably produced the stains on the surface of its decompo- 
sition. Iam informed by Mr. Campbell, who collected this specimen, that it occurs in a granite 
rock which underlies a thick mass of red sandstone and beds of limestone. These strata are 
nearly one thousand feet thick, and rest horizontally on the granite. They form the margin of 
an extensive mesa formation, stretching far northward towards the great cañon of the Colorado 
river. He also states that quartz veins or "7 ledges” are common in that region, and that the 
^ country presents many indications of the presence of gold. The specimen in hand is too com- 
pact and hard to be regarded as auriferous, but yet may be a portion of a gold-bearing vein, 
and the former presence of pyrites is a good indication. "The mica crystals in this specimen are 
interesting for their well-marked crystallization. "They have the usual form of Muscovite micas, 
the regular rhombic prism. 
No, 5. Pueblo creek.—This specimen, although apparently from the same region as No. 4, 
and containing a similar silvery mica, differs from it in containing a large portion of feldspar, 
which, with the quartz, renders it a coarse-grained granite, and it is so labelled by Mr. Marcou. 
The mica is found at one side of the specimen only, and thus indicates that it formed part of 
the wall of a vein. 
No. 6. Sierra Madre, Agua Fria.—This specimen may be considered to be a very coarse- 
grained granite. It consists chiefly of feldspar, of which mineral there are two varieties ; one 
white, and cleaving with broad, flat faces, and the other flesh-red, and in smaller and less regu- 
lar masses. Quartz, in coarse grains—some as large as the end of one’s thumb—is found with 
this feldspar. A white silvery mica is also present in small quantity, but is not in defined crys- 
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