In attending the Tucson “main show” I remained on a
hunt for the best $5 mineral I could find at the venue. Now, there are very few $5 minerals for sale
in the Convention Center but there are numerous five figure minerals a buyer
could take home! But, the hunt is the
fun part of the chase and I brought home some nice crystals of lazulite a
magnesium, iron, aluminum phosphate [(Mg,Fe++)Al2(PO4)2(OH)2]. Lazulite is often a sky-blue to azure-blue
color but my crystals are such a very deep blue or blackish-blue that the
camera will not pick up such---as is the case for crystals collected at the
well-known Rapid Creek locality in the Yukon, Canada. Crystals from Rapid Creek
are stubby bipyramids, have a vitreous luster and are transparent to
translucent. On the Rapid Creek crystals
a strong light will transmit through the specimens and produce the beautiful
blue color. Crystals are fairly hard at
5.5-6.0 (Mohs).
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| Bi-pyramidal crystals of deep blue to black-blue lazulite (L) and quartz (Q) collected from Rapid Creek, Yukon Territory, Canada. Width of specimen ~1.75 cm. |
Luzulite is found in high grade metamorphic rocks
where it is associated with kyanite, corundum, andalusite and others. It also may be found in some massive
hydrothermal pegmatites. The magnesium-rich lazulite is in a solid solution
series with the iron end member scorzalite [(Fe++,Mg)Al2(OH,PO4)2].
 |
| Two photomicrographs picking up the dark blue color of lazulite crystals, each has a maximum width of ~ 3 mm. Also present are tiny terminated quartz crystals. |
It is easy to confuse lazulite with lazurite, a blue
variety of the mineral Hauyne, a sodium-calcium tectosilicate with sulfur,
sulfate and chloride. Lazurite is found
associated with pyrite in zones of contact metamorphism of limestone and is the
major “blue” component of lapis lazuli (a mixture of lazurite, pyrite,
calcite).
In my hunt for the best $5 mineral at the different show
venues, I sought advice from a friendly Arizona rattlesnake:
· Be
flexible
· Keep
a low profile
· Think
before you strike
· Soak
up some sun
· Shed
your old ways
· Be
thick skinned
· Don’t
get rattled