Page 99 - Volume 3 - Walks In The Black Range

There is, apparently, a moonstone deposit in the park. Moonstone occurs in pegmatite, formed when the pegmatite magma rapidly cooled. Sanidine is the mineral, Moonstone is a variety (KAlSi3O8). The deposit was discovered in 1925 and the crystals were fairly long 8” to 4’. However, as James D. O’Brient notes in “Preservation of primary magmatic features ... Rabb Park, New Mexico”:
“Rabb Park moonstone specimens are well known to mineral collectors because of their gem-quality blue schiller, but could never be profitably mined because of widespread fracturing that has broken most of the pegmatite crystals into pieces less than I cm in maximum size.”
The paper may not encourage you to go for a dig but it is very interesting geology, something that is characteristic of the Black Range.
The open area of Rabb Park is quite beautiful with tall Ponderosas and small streams (see photo below). We were there in November, April (if there was snow in the mountains) would be nice as would the monsoons, if they occurred.
Enjoy your walks in the Black Range.
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