just got back from spending Christmas week in Hawaii and was once again amazed
by the rock formations and lush landscaping I saw there!
is me six years ago 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. I'd been hoping to do it again, but I was told that you
can't do that lava tube anymore, it's under the recent lava flows. It is a reminder to all of us not to wait to get out and see the natural wonders of our planet. They may seem like they'll be there forever, but changes are always happening--and we never know where or when.
When I was in Hilo, I visited the Lyman Museum (look
for a review of it in an upcoming Rock & Gem). Not surprisingly, it
features some volcanic materials.
The museum displayed “volcanic bombs” from eruptions. These are composed of basalt. When
the liquid is shot into the air, it comes together, twists around, and falls to
earth. The shape tends to be oval, like a football. The bomb may be solid or
hollow and they are collected as oddities for their shapes and textures.
|Volcanic Bomb at Lyman Museum|
Volcanic bombs and small sharp black
splinters are not the only interesting form that falls from the eruptions.
There is also Pele’s Hair, Pele’s tears, and spatter. The hair is formed when
lava is flying through the air and it stretches because it’s still molten. The
resulting thin strands are glass and they sometimes have a droplet at the end.
Some call those droplets Pele’s Tears. Frankly, Pele's Hair looks a bit like the hair I take out of my hairbrush; silvery gray with a touch of brown.
Another formation that is called Pele’s
Tears is the peridot crystals that can form in olivine. The spatter is exactly
what it sounds like, bits of lava that fall to the ground.
|Pele's Hair from Lyman Museum|
PLACE FOR LAPIDARIES
The Hawaiian Islands are fascinating for many reasons, especially the chance to
see geology in action! It does have some minerals that lapidary artists and
mineral collectors look for, but they are largely in microscopic amounts of
labradorite, feldspar and plagioclase. The one you’re most likely to find is
olivine. Olivine is a green mineral that has very little silica and a lot of magnesium
and iron. It is the least stable mineral on the earth’s surface; when olivine
gets weathered, it pseudomorphs into iddingsite. While olivine is a
mineral because it has an identifiable crystalline structure, iddingsite passes
through many phases of change and so it is referred to as a rock, not a
mineral. When the olivine is mixed with pyroxene, it becomes peridot.
|Olivine with a few Peridot crystals|
Lapidaries have been known to work with basalt when it is dense enough. It will be black and
probably have visible dots of other minerals in it and take a nice shine.
Because basalt can be light and fluffy as Scoria and goes on a scale to very
dense, it doesn’t have a Mohs scale number.
Full disclosure: Some of the information in this blog post appeared earlier in an article I wrote for Rock & Gem Magazine. I took the pictures of the Volcanic Bomb and Pele's Hair at the Lyman Museum where I took a whole lot of pictures for the upcoming R&G article.
Show Season is in full swing now. Don't miss the chance to see and acquire amazing specimens, slabs, and rough! Send me a picture of your favorite!
Until next time, Your Lapidary Whisperer,
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