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Tilly Foster Mine Page 1
The Tilly Foster Mine was developed in a magnetite deposit in
gneiss located on the northeastern edge of the Hudson Highlands
geologic province, an extension of the Reading Prong of New
Jersey and Pennsylvania. The province is interpreted as a meta-
morphosed sedimentary sequence representing the cores of
mountains formed by a continental collision during the Grenville
orogeny, some 900 million to one billion years ago. Operated from
the 1850's to 1895, the mine produced a low phosphorus iron ore
well suited to making Bessemer steel. After an 1895 accident in
which 13 miners were killed, the mine was closed. Tilly Foster was
noted for chondrodite (some of the world's best), clinochlore,
dodecahedral magnetite, and brucite specimens. Serpentine
pseudomorphs are classic Tilly specimens and the yellow titanite
specimens from Tilly are rare and highly sought after.
M1602
TITANITE
Tilly Foster Mine,
Brewster, NY, USA
Gemmy yellow titanite crystal in calcite
cleavage with minor clinochlore.
.
Specimen size - approx. 6.5 cm. X 6.2 cm. X 3.0 cm.
M1591
BRUCITE
Tilly Foster Mine,
Brewster, NY, USA
Pale green and white brucite crystals in a
seam in lean gneissic magnetite ore. This
brucite does not fluoresce.
Specimen size - approx. 12.5 cm. X 9.0 cm. X 7.0 cm.
M0808
MAGNETITE
Tilly Foster Mine,
Brewster, NY, USA
Large dodecahedral magnetite crystal with
small clinochlore crystals on lean magnetite,
chondrodite ore.
Specimen size - approx. 7.3 cm. X 4.7 cm. X 4.5 cm.
M0743
MAGNETITE, CHONDRODITE
Tilly Foster Mine,
Brewster, NY, USA
Small dodecahedral magnetite cystals, chondrodite
crystals on gneissic magnetite, chondrodite ore.
Specimen size - approx. 5.5 cm. X 5.5 cm. X 4.3 cm.
Sorry, the mineral specimens on this page are not for sale. Chondrodite for sale
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