Dominion Gulf Company claims, Lackner Township, Unorganized North Sudbury District, Sudbury District, Ontario, Canadai

Regional Level Types
Dominion Gulf Company claims	Group of Claims
Lackner Township	Township
Unorganized North Sudbury District	District
Sudbury District	District
Ontario	Province
Canada	Country

The mineralization is hosted in a very fine-grained black syenite with approximately 40% feldspar with hornblende, augite as the main mafic minerals. Some feldspathoid is reported and abundant magnetite is disseminated in the rock. The deposit is associated with the Lackner Lake alkalic complex. The complex consists of peripheral and core nepheline syenites separated by a partial ring of alkalic mafic rocks (ijolite and malingite). Dikes of magnetite and apatite cut both the mafic and syenitic phases of the complex. Lamprophyre dikes also reportedly cut the complex. The Lackner Lake complex is enclosed within the gneissic rocks of the Kapuskasing Structure.

The nepheline syenite is coarse-grained with zoned subhedral apatite, partially surrounded by orthoclase latsh, both of which are replaced in part by nepheline. Mafic minerals are interstitital and consist of clinopyroxene, biotite and magnetite. Closer to the mineralized zones, the rocks are finer grained, richer in sodic pyroxenes and have a granoblastic texture. The composition of these rocks is mafic nepheline syettie or malingite.

The apatite mineralization is hosted in a very fined grained black syenite with approximately 40% feldspar with hornblende, augite and biotite as the main mafic minerals. Some feldspathoid is reported and abundant magnetite is disseminated in the rock. The nepheline syenite is coarse grained with zoned subhedral apatite, partially surrounded by orthoclase laths both of which are replaced in part by nepheline. Mafic minerals are interstitial and consist of clinopyroxene, biotite and magnetite. Detailed petrographic work has been published by Parsons (1961), Hodder (1958) and Sage (1983).