Bauer et. al. (2003) say the following about the Sandia Granite:
“Sandia Granite is quite variable in mineralogy, but on average consists of 35% quartz, 15% microcline [a potassium-rich feldspar], 35% plagioclase [also a feldspar, calcium- or sodic-rich], 10% biotite, and 5% microperthite [another feldspar]. This makes it a quartz monzonite to granodiorite. However, true granite compositions are rare throughout the world, so geologists tend to use the term granite broadly for any crystalline, quartz-bearing plutonic [i.e., not volcanic] rock”. Generally, the type and relative proportions of potassium-rich and calcium/sodium-rich feldspars dictate whether the “technical” description of this type of formation is a granite, monzonite or granodiorite.
Connell (2006) describes the Sandia Granite on his map legend as the following:
“Pink … biotite monzogranite and granodiorite…”. But the Sandia Granite is not always pink, and can be a beautiful white granite, as you will see if you hike up nearby Rozamiento Canyon!
Hedlund (1985) provides this:
“Sandia Granite…ranges in composition from a two-feldspar granite to quartz monzonite to granodiorite. Commonly contains 15-40% microcline [a potassium-rich feldspar]…30-45% oligoclase [a sodium-rich plagioclase feldspar]…20-35% quartz, 7-10% biotite…[and small amounts of numerous accessory minerals]. Hedlund, in turn, makes references to prior studies. Indeed the geology of the Sandias and surrounding region has been extensively studied, and I’m certainly not well-versed in understanding it all, and I’m also not an igneous petrologist. Nevertheless, the Sandia Granite provides a fun terrain and substrate for hiking/geocaching, whether or not it’s a Granite, or a granite!
To get to this cache you can follow the instructions for getting to the “Gneiss Views!” cache further south. As you go north along the pleasant ridge hike, toward “What a Pile of Schist!”, before the going starts to get noticeably steeper, you can start cutting over toward the northeast and cross the drainage where it is not too deep at all to reach the cache, on a local ridge. This cache location is clearly in the Sandia Granite, well east of the surface contact with the older Metamorphic rocks. See the geologic map attached to this cache description for an illustration.
Bauer, Paul W., Richard P. Lozinsky, Carol J. Condie and L. Greer Price, 2003, Albuquerque A Guide to Its Geology and Culture, New Mexico Bureau of Geology and Mineral Resources.
Connell, Sean, 2006, New Mexico Bureau of Geology & Mineral Resources, Open-File Report 496: Preliminary Geologic Map of the Albuquerque – Rio Grande Metropolitan Area & Vicinity, Bernalillo & Sandoval Counties, New Mexico.
Hedlund, D. C., 1985, Geologic Map of the Sandia Mountain Wilderness, Bernalillo and Sandoval Counties, New Mexico, U.S. Geological Survey.
CONGRATULATIONS TO BUDABELI AND THOEHN FOR THEIR CO-FTF!