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Spatial Coverage is exactly "Powderhorn, CO"
Iron rich Carbonatite.
All weathered faces of the rock show heavy traces of oxidation.
Dark gabbro dike separating ijolite and uncompahgrite
Rock is comprised almost entirely K-Feldspar.
Three hand samples from different facies were collected to represent this sample. Out of two of the largest samples one is a dark fine grained rock while the other is coarse grained. Both contain large (5-8 mm) clusters of biotite.
Large (1 cm-2 cm) dark grey to translucent quartz crystals comprise the matrix of the rock. Melilite minerals propagate consistently paralell to one another throughout the rock.
Coarse grained pyroxenite showing heavy traces of oxidation on every weathered face of the rock. Large clusters (5-8 mm) of biotite appear throughout the rock.
Chert sample found in a Carbonatite.
Pink to light brown chert sample that contains small (< 1 mm diameter) vesicles. Very thin quartz veins propagate through the sample in no preferred orientation.
Light brown to almost off-white fine grained Carbonatite. Delicated Barite appears in very thin layers on one side of the rock.
Composed entirely of Ilmenite.
Recently exhumed ijolite from shallow bulldozer cut.
Hand Sample: Shows traces of iron oxidation in isolated areas. Small (> 0.5 mm in diameter) nodules, with the appearance of small sand grains appear in clusters on one face of the rock (not…
Nepheline Syenite. Thin, dark vein runs through the center body of the rock.
Nepheline syenite that outcrops on west side of trail at about 9200 ft. on east side line of section.
Fenitized Gneiss. Gneiss discovered in direct contact with pyroxenite in prospect trench on ridge, about 500 ft. west of PH-1.. .
Coarse pyroxenite, with traces of nepheline. This is the freshest pyroxenite that was found. It occurs near the nepheline syenite body in the eastern part of the complex.