Wednesday, May 23, 2018


This is me holding up the side of a lava tube at the Thurston Lava Tube also called the Nahuku in Volcanoes National Park on the Big Island.  

One good thing about the volcano erupting on the Big Island of  Hawai'i right now is that its doing something lapidaries love--creating new rocks! 

Unfortunately, most of it will be Basalt, the ugly cousin in the rock family. Basalt is the stuff you see hardened over the current lava flows, but it can hide some lovely secrets! 




Volcanic rocks originate from igneous magma within the earth's crust. When most of us lapidaries think of volcanic rocks, the first thing that comes to mind is Obsidian; that beautiful black/brown glass rock that makes magnificent cabochons.


However. . . Obsidian isn't all that common in Hawai'i. It's only found at the  Pu'u Wa'awa'a Volcano on the west side of the Island of Hawai'i. The current eruptions are at Kilauea, on the eastern side. 


After the Mt. St. Helens Volcano erupted, some clever glass makers created ornaments from the ash, so I decided to find our if the ash or Basalt from Kilauea was good for that. I'm not a glass maker, but I sure enjoy making  cabs from slag glass! 


No such luck, a phone call to Hot Island Glass, a glass studio in Maui let me know that the Hawai'ian  lava Basalt doesn't have enough silica for art glass.



Olivine on Basalt from Hawaii  

There are several lovely minerals found in the Hawai'ian Islands, including Jasper, Sunstone, and Labradorite, but for my money, Olivine is the most interesting.


Olivine can be found in basalt and it is the mineral that can become the gemstone Peridot. 


Island legends say that Peridot is the tears of the goddess Pele. 


Peridot is a 7.0 on the Mohs scale, about the same hardness as Jasper. so it can be cabbed, but the remarkable translucent properties it can have also make it appealing to faceters. It is known as the gemstone for August birthdays. 


The green stone in this ring is faceted Peridot sitting on an Olivine and Basalt  specimen.


A lot of Peridot is found at the Diamond Head landmark in Oahu. It's often called the "Hawai'ian Diamond".





This beautiful mineral is also found in Basalt flows. It comes in a range of colors and translucency's from absolutely clear to milky peach with some browns and reds. When you look at it from different directions, you are likely to see a "spangled" flashing of light.





Labradorite is also formed in Basalt and has been found in the Hawai'ian Islands - although probably not this piece from my collection. 






Travel Tip!

If you get a chance when you're in Hawai'i, try to get by the Papakolea Beach in Mahana Bay where the sand is green because of all the tiny Olivine crystals found there.

No less dramatic are the black sand beaches (Basalt sand) found on several islands. This sand is formed when the hot lava falls into the ocean and explodes from the temperature difference and is ground into ever smaller pieces by waves.


That's all for today. Until next time, I'm your Lapidary Whisperer, 












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