Northern Queensland fossicking

Mount Gibson near Innot Hot Springs is well known by fossickers as a collecting locality for gem topaz.

Access

Innot Hot Springs is on the Kennedy Highway between the small townships of Mount Garnet and Ravenshoe. Mount Gibson is about 5km north-west of Innot Hot Springs.

From the highway take the Broken Gully Road and travel 1.7km to a grid/steel gate (please close gate upon entering) and continue to the main entrance sign at Condon Gully. See map below for details of tracks in the fossicking area.

Conventional vehicles should only go as far as Gibson Gully. Access by foot or 4WD vehicle is recommended beyond this point as tracks to the main diggings are steep and gully crossings are very rough, with many washouts occurring after rain.

Map

• Mount Gibson fossicking area map (PDF, 787.3 KB)

Facilities

Camping is not permitted. Accommodation is available in Innot Hot Springs.

Fossicking notes

Mount Gibson consists mainly of hornfels resulting from thermal metamorphism of sedimentary rocks of the Silurian to Devonian Hodgkinson Formation by a composite granite batholith of Permo-Carboniferous age. The hornfels occurs as a pendant within the roof zone of the batholith that, in this area, comprises a medium-grained alkali feldspar granite (Pinnacles Granite) and smaller bodies of microgranite, pegmatite and aplite.

Late stage topaz-bearing intrusions related to that appear to be the source of the gem topaz and associated cassiterite. Much of the area is strongly mineralised and many of the creeks and gullies in the vicinity have been worked for alluvial tin (cassiterite).

Topaz, quartz and cassiterite are the main minerals found. Crystals showing good forms and clarity are common. Topaz is usually colourless but rare golden and blue colours have also been found.

Diggings are located on the lower slopes of Mount Gibson to the south-east of the trig station. This area is known as Glittering Star and contains numerous shallow pits, trenches and shafts.

Other diggings referred to as Patricia (The Crystal and Pattersons) are located less than 1km to the west. Shallow pits and trenches have been worked in 2 adjacent areas on the northern side of a small north-westerly trending ridge. At the north-western end (The Crystal), massive white quartz crops out prominently. Several shallow pits have been dug in search of vughs in the quartz outcrop but most of the pits are located in the scree slope below. Further to the southeast (Pattersons) shallow pits have been dug in scree material and quartz-greisen rock, which contains many vughs and possibly crystals.

Simple dry sieving methods are used to search for gems, as water is generally scarce.