A Heritage Trails sign once stood in front of Gemstone Beach but it is no longer there (see photo above, left). It noted that some of the “gems” to be found on this beach include “Hydrogrossular, Jasper, Garnet Sands, Rodingite, Epidote, Fossil Worm Casts, Idocrase, and Sapphire”. Of course, garnet sand is too small for tumble polishing, but the others sound promising. In her 1981 book, “The New Zealand Rockhound”, Natalie Fernandez lists Orepuki in her “Locations” chapter and states that the following can be found there: “Hydro-grossular garnet, orbicular jasper, garnet sands, rodingite, quartz dolerite pebbles, garnets, quartz, semi-nephrite, and fossil worm casts” (see photos below, left). Jocelyn Thornton has an entry on “Orepuki – Beach Pebbles” in her 1985 booklet “Gemstones” (also available online here). Her book is written for the beach stone fossicker and lapidarist (cutter and polisher of stones). She refers to grossular garnet, granite, gabbro, “altered volcanic rock with infilled bubbles”, rocks with worm trails and epidote, conglomerate, and orbicular jasper with metallic hematite (see photos below, right).
When I made my first couple of visits to Gemstone Beach, I had high hopes of finding something spectacular. That didn’t happen. Although I did manage to find fossil worm cast stones easily enough, and some nice stained quartz and dark red jasper. But it took me a number of visits, conversations and a bit of research to eventually be able to recognise hydrogrossular garnet stones. I have now also found a handful of orbicular (poppy) jaspers. Hours walking the beach, plus persistence, patience and research, have all paid off in the end. Over the past few years, I have found some very nice stones on Gemstone Beach, and it is my favourite fossicking site.
I once prepared an introduction to Gemstone Beach stones for a small retail outlet in Riverton that stocked a few I had polished. In that brief information pamphlet I wrote: These are tumble-polished naturally-occurring stones from Gemstone Beach. They were picked up while I walked along the beach, carefully observing wet stones (and dodging waves), selecting those with interesting colours and patterns. I then used a small rotary tumbler to smooth and polish them over a period of four weeks. The tumbler simulates the actions of the waves but intensifies it. In many instances, I do not know the exact type of rock from which the stones come. Each stone is unique but carries within it a significant part of New Zealand’s geological history. Each stone also tells its own story upon careful reading, and every person can see slightly different messages, landscapes, patterns and depths. These are the real gems of Gemstone Beach.
As time has gone on, I have been doing research on the different types of stones to be found on Gemstone Beach. A five-part Series of Posts that incorporates what I now (May 2025) understand about some of the stones starts with this one, “Thirty Gemstone Beach Pebbles for Doug: Part One – Stones 1 to 5”.
Many of the stones I have found on Gemstone Beach are not identifiable by me – I collect them and polish them because they are beautiful, intriguing and/or interesting. But I also find quite a number of stones that I think I can identify. The main types are listed below, in alphabetical order. Click on a stone for more information about it [Note: Links with * after them, e.g., Argillite*, have not yet been constructed. Some stone types for which a page has not yet been developed below may include links to TumbleStoneBlog Posts referring to such a stone.]
Amygdaloidal Stones (Volcanic with infilled bubbles)* Blog1 Blog2
Argillite* Blog1 Banded Argillite1 Banded Argillite2 Banded Argillite3 [Gn8 to Gn14] Spotted Argillite [Gn20 to Gn33]
Banded Ignimbrite* Blog1 Blog2
Breccia* Blog1 Blog2 Blog3
Conglomerate* Blog
Fossil Coral* Blog
Fossil Worm Casts (Trace Fossils)* Blog1 Blog2
Granite* Blog1 [W77 to W80]
Hydrogrossular Garnet
Igneous (Black & White)* Blog [W43 to W63]
Jasper* Blog Brecciated Jasper Hematite Jasper Orbicular Jasper Poppy Jasper
Porphyry* Blog [Stone #2]
Quartz* Blog1 Blog2
Quartzite* Blog [Stone #9] Blog2 [Stone #25] Blog3
Rhodonite* Blog1
Rhyolite*Blog1
Sapphire
Thulite* Blog1 Blog2 Blog3
Unakite* Blog [2nd stone]
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