Showing posts with label lapidary. Show all posts
Showing posts with label lapidary. Show all posts

Wednesday, December 23, 2015

December Blues



Day 71: If you were born in the month of December, you are more fortunate than most when it comes to a selection of birthstones. There are three choices: blue zircon (if your taste runs to faceted stones), turquoise (for a more earthy look) and the classic elegance of lapis lazuli.

I bring this up because a friend just asked me if I could verify that a piece she owns is in fact lapis. I have not seen it yet, but I did advise her that there are a number of imitators (most notably, dyed howlite), but all lack the telltale flecks of pyrite which distinguish much true lapis. Lapis aficionados will argue whether or not pyrite is desirable and to my way of thinking, it's a matter of personal preference. I like it. On the other hand, the stonecutter is more likely to say that good lapis excludes pyrite because it makes it more difficult to grind and polish due to undercutting of the softer material.

I sold my rockhounding gear years ago after deciding that creating cabochons such as these was not worth the hours spent with wet, cold hands, but I kept much of my more valuable rough including a stash of genuine lapis. In any event, I seldom wear jewelry and get more pleasure from seeing the raw minerals in my collection.

Thursday, September 18, 2014

Lovely Lapis Lazuli


Day 353: My interest in rocks began at a very early age, and by the time I was nine years old, I had a mineral collection which (to my mother's dismay) covered the top of my dresser. Each specimen was labelled with what I believed it to be (often erroneously) and where I had found it. As I grew to be an adult, I developed an interest in stone-cutting as an adjunct to rockhounding, and was not content to work simply with slabs of agate or pieces of Australian opal. One of my favourite stones was lapis lazuli.

Lapis is somewhat difficult to work. Pyrite inclusions are desirable; veins of quartz are not. Both create problems for the lapidarist in that they are softer or harder than the blue matrix material. I was quite proud of the uniform finish I achieved on this particular stone (a 20 x 30 mm. cab).

Fake lapis abounds in the jewelry market. Most often, it will be blue-dyed howlite. However, although howlite also contains quartz, it never contains the pyrites which typify true lapis.

Wednesday, February 19, 2014

Hard Rock Mining


Day 140: By special request: rocks and a rockhounding story.

In 1972, a deposit of amethyst quartz was discovered by a farmer near Big Lake, Washington (Walker Valley, Skagit County). A few years later, my husband and I became aware of the site through a friend who ran a lapidary shop. Avid rockhounds that we were, we made several field trips, Bruce keen on finding some faceting-grade crystals while I was more interested in collecting mineral specimens for display. Although Bruce's hopes for flawless material were never realized, we did gather both clear quartz and amethyst, and also some nice calcites (the yellowish "roses"), but the "digging" was not easy. The crystal vugs were set in a very dense basalt and had to be sledgehammered and pried apart with long crowbars.

The specimens shown here all came from one of our most successful digs. It was also the most physically demanding, and blisters, nicks and slices from sharp rock edges were par for the course despite whatever protective gear we wore. During the brutal excavation of the amethyst, a fragment of basalt embedded itself in the edge of my lower lip. I didn't notice it until a few days later, and then assumed that it was just a scab. By the time I realized it was a piece of rock, it had healed over, leaving a little spot like a blackhead which I could not squeeze out. Six months or so went by, and although it didn't cause me any particular discomfort, it bothered me that it was there.

I'm not particularly squeamish unless the blood I'm seeing is my own, so when I decided to do a job of home surgery to remove the chip, I laid out my tools (Exacto knife, tweezers and a needle) on the bathroom sink and closed the lid on the throne in case I started to pass out. It was a good precaution to take, because I got light-headed several times before extracting a tiny sliver of black basalt sharp as a splinter from a razor blade's edge half an hour later.

Walker Valley is now only open to permittees (yeah, another permit), and I understand it still yields some nice specimens of amethyst and clear quartz, but I'm content with those I dug forty years ago. I still collect rocks, but only those I can easily pick up off the ground.