English: Blue calcitic marble (8.0 cm across at its widest) from the Precambrian of New York State, USA.

This remarkable specimen of blue marble comes from the Valentine Mine in New York State, an active wollastonite mine/quarry. Wollastonite is a calcium pyroxenoid, formed by hydrothermal metamorphism (metasomatism) of marble by hot, silica-rich fluids. Blue calcitic marble is the proximal host rock to the Valentine Wollastonite Skarn Deposit; white calcitic marble occurs distally.

Published analysis shows that blue marble host rocks around the Valentine Wollastonite Skarn Deposit are >98% calcite with minor diopside and graphite. The bluish color may be due to the presence of sub-microscopic graphite inclusions in the calcite crystals.

The Valentine Mine is localed at the intrusive contact between Grenvillian marbles of and Diana Complex syenites (1.118 Ga). The wollastonite skarn is synchronous with the intrusion of Diana Complex syenites (see Gerdes & Valley, 1994), so it also dates to 1.118 Ga (late Mesoproterozoic). The blue marble host rock is slightly older, at about 1.13 to 1.16 Ga.

Age: late Mesoproterozoic, 1.13-1.16 Ga (granulite facies metamorphism to marble during a phase of the Grenville Orogeny)

Locality: Valentine Mine (Gouverneur Talc Company No. 4 Quarry) (wollastonite mine), ~0.75 to 1 mile from the southern side of Lake Bonaparte, ~3.5 air miles southwest of Harrisville, northern Lewis County, northern Adirondack Mountains (northwestern Lowlands, near the Lowlands-Highlands boundary), northern New York State, USA

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Info. partly synthesized from:

Basu, A.R. & W.R. Premo. 2001. U-Pb age of the Diana Complex and Adirondack granulite petrogenesis. Proceedings of the Indian Academy of Sciences (Earth and Planetary Sciences) 110: 385-395.

Gerdes, M.L. & J.W. Valley. 1994. Fluid flow and mass transport at the Valentine wollastonite deposit, Adirondack Mountains, New York State. Journal of Metamorphic Geology 12: 589-608.