Goldie
Narrow bands of carbonatite up to 0.7 m thick and 100 m long are associated with carbonated lamprophyre dykes. Wall rock gneisses are fenitized with the formation of riebeckite, aegirine and red K-feldspar.
Narrow bands of carbonatite up to 0.7 m thick and 100 m long are associated with carbonated lamprophyre dykes. Wall rock gneisses are fenitized with the formation of riebeckite, aegirine and red K-feldspar.
At McCoy Gulch carbonatite occurs as small lenses in lamprophyre and as a 0.6 m thick dyke. In the dyke the carbonatite develops granular, colloform and brecciated variants and consists mainly of calcite with hematite and a little baryte, apatite, magnetite, pyrite and feldspar.
This complex, located in the Wet Mountains of Colorado, has two centres; to the southwest is a complex of nepheline syenites and ijolites distributed around McClure Mountain, while in the northeast, around Iron Mountain, is a predominantly ultramafic complex of layered pyroxenites.
Covering just over 3 km2, Gem Park is a funnel-shaped body emplaced in Precambrian gneissic granite, granite gneiss and amphibolite, which on the southern side is overlain by Tertiary latite flows, rhyolitic welded tuffs and water-laid tuffs.
The complex at Democrat Creek covers 9 km2 and is composed predominantly of quartz syenites together with breccias and a mass of mafic and ultramafic rocks to the south.
Within the dyke swarm that radiates from the stocks at Spanish Peaks are alkaline types including fourchite, teschenite, shonkinite and mela- and microsyenite. K-feldspar is present in most of these dyke rocks together with analcime, and pyroxenes which vary from diopside through to aegirine.
The Raton-Clayton volcanic field covers nearly 2 000 km2 in northeastern New Mexico with a small area extending northwards into Colorado.
A post-Precambrian, pre-Pennsylvanian melteigite dyke or sill and a carbonatite dyke have been recorded in the Monte Largo Hills northeast of Albuquerque (Lambert, 1961, quoted by Loring and Armstrong, 1980, p. 347).
This syenite outcrops over an area of 3000x220 m and apparently intrudes Precambrian schists.
Two approximately east-west-trending syenite dykes 1.5 km long and 1.5-5 m thick cut Precambrian quartz-sericite and quartz-chlorite schists. A similar dyke occurs 4 km to the south.