WGNHS
Wisconsin Geological and Natural History Survey

Titanite

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Thin section of high relief brownish titanite growing around black ilmenite. Also shows darker green hornblende, light green chlorite and brown biotite mica. Plane polarized light. Field of view is about 4 mm left to right. Opelt Quarry, near Neillsville, Clark County, Wisconsin. W. Cordua image.

Formula: CaTiSiO5 Monoclinic

Description:Titanite is a common accessory mineral usually found as tiny grains in many different rocks. It is common in plutonic igneous rocks such as granite, diorite and syenite. Titanite also is a common accessory in metamorphic rocks such as gneiss, schist or marbles. In some marbles, the crystals may be large. Titanite survives weathering sufficiently to be found as a heavy mineral in sediments and rocks such as sandstone. Titanite is present in many of Wisconsin’s igneous, sedimentary and metamorphic rocks. Generally the grains are so small that the mineral is overlooked until thin section investigation is done. Only a few of the state’s many titanite occurrences are listed below.

ADAMS COUNTY: Tiny brown to violet crystals occur in vugs with quartz, calcite and pyrite in granite cutting quartzite in the quarry at Hamilton Mounds, SE NE sec. 36 T.20N. R.6E. (Buchholz, 1992, pers. comm.).

FLORENCE COUNTY: Titanite is a widespread accessory in the Marinette quartz diorite, where it may locally make up 6% of the rock. The rock can be found in railroad cuts in the SW NE sec. 18 T.38N. R.20E. It can also be found in outcrops in SE SW sec. 33 T.38N. R.20E. (Sims, et. al., 1992).
– Titanite is a component of the Dunbar Gneiss, where it may form up to 5% of the rock, such as in outcrop in the SE NW sec. 15 T.37N. R.18E. (Sims, et. al., 1992).

MARATHON COUNTY: Titanite is a common accessory in the rocks of the Stettin pluton, where it may form crystals as much as 2 cm. in diameter. It is particularly common in nepheline syenite pegmatites of this body (Falster, et. al., 20000).
– Titanite is found as crystals up to 7 mm long in the nepheline syenite in the zircon mine in SE SE sec. 22 T.29N. R.6E. (Sood, Myers, and Berlin, 1980).
– Titanite occurs in crude black crystals up to 1 cm. long in dikes cutting the north part of the Wausau pluton, such as is exposed in the “rotten granite” quarries south of Rib Mt., sec. 19 and 20 T.28N. R.7E. (Falster, 1987).

MARINETTE COUNTY: Subhedral to euhedral titanite is a common accessory in the Hoskins Lake granite. Good exposure of titanite-bearing granite occur near Niagara in the S 1/2 sec. 12 and the N 1/2 sec. 13 T.38N. R.19E. and NE sec. 17 T.38N. R.20E. (Prinz, 1965).

PORTAGE COUNTY: Titanite occurs in the Red River Adamellite as exposed in a sand pit, center sec. 18 T.24N. R.8E., north of Stevens Point. (Greenberg, et. al., 1986).

WAUPACA COUNTY: Titanite is common in the rocks of the Wolf River Batholith exposed throughout the county. Some localities of titanite-bearing rock, as noted by Greenberg, et. al.(1986) are:
– in the Rapakivi Waupaca Adamellite, in a quarry in the NW NW sec. 4 T.22N. R.12E., about 6 km. north of Waupaca.
-in outcrops along the Little Rib River, south of Big Falls, SE SE sec. 26 T.25N. R.12E.