For a small island destination, Flinders Island is rich in opportunities to explore unique geological, environmental and nature more generally. There are ten geosites located across Flinders Island where you can explore at your leisure, and often in complete isolation, and learn about the stories that define the landscape of magnificent Flinders Island. The Killiecrankie Diamonds are perhaps the best known of Flinders Island geological features.
Killiecrankie is located on the northwest of Flinders Island, and became an object of geological interest in the early 1800s the Killiecrankie ‘diamond’ was found – it’s not indeed a diamond, but a form of topaz. Today the granite ranges that are home to Mt Killiecrankie and nearby Mt Tanner make the location one of Flinders Island’s best known scenic attractions, and a popular destination for visitors to explore.
The granite and associated ‘pegmatites’ in the Killiecrankie area have been exposed and weathered at the earth’s surface over millions of years. Today, most topaz is recovered from recent sand and gravel-rich deposits. Quartz, tourmaline, cassiterite and blue beryl are also associated with the topaz and common in the area. There is a designated fossicking area on the north side of Killiecrankie Bay where you can prospect for topaz – you can hire equipment locally. Certain specimens are prized by gem collectors and are regularly used in the making of jewellery. See: Furneaux Geotrail
By contrast to KIlliecrankie in the north, Lady Barron is located at the south of Flinders Island. More recently formed rocks on the island are there for you to explore at Yellow Beach near Lady Barron and that overlooks the sheltered channel waters of Franklin Sound. Here you will find sandstones rich in dark organic matter at the rear of the beach where the sand is stained with the residue of recent erosion of this rock feature. Other types of rocks to look our for are Mathinna Beds and Granites of varying types.