Natrolite Crystals From Peats Ridge Quarry N.S.W.

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Syndyne

Shaun Galman
Joined
Apr 9, 2013
Messages
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Location
Lightning Ridge, N.S.W.
Hi all,

Finally got around to getting a few quick snaps of the Natrolite specimen to share here.

This piece was found at the Peats Ridge Basalt Quarry in 1967 while my father and uncle were searching the area for good crystal specimens with another friend by the name of Tom, who also collected minerals and knew about the good crystal specimens in the area.

They had search unsuccessfully for the entire day until they came to a small clearing not far from the quarry where, while resting, my uncle sat on a large piece of hard Basalt stone. Tom had noticed a fine white indicator line running across the boulder he was sitting on so they immediately hit it with the sledgehammer and inside was a quite large geode of microfine Natrolite crystals about ten inches in diametre. Unfortunately the geode had broken into several smaller pieces -usually the result when the host rock is so hard. Tom took the largest piece and we ended up with this pretty decent sized piece also.

My uncle sealed the specimen in a glass case he made at the time as the crystals are as fine as human hair and can break off with the slightest breeze. It has remained unchanged to this day.

I've looked after this specimen after they passed it down to me at age seven (only a year or two after starting my mineral obsession) and It's been well looked after ever since, to the point where I haven't noticed any further crystal loss.

Apologies for the lesser photo quality. It's pretty hard to photograph anything through glass, particularly with the iPhone. But they should give a decent idea. This specimen is about 150mm (six inches) in length and about 90mm (three and a half inches) high at the tip. The crystals vary in height but most are about 20mm (three quarter inches) or so.

1376540245_natrolite1_copyshaun_galman_2013.jpg

1376540366_natrolite2_copyshaun_galman_2013.jpg

1376540391_natrolite3_copyshaun_galman_2013.jpg

The glass case with the old (label maker) name that has really stood the test of time! :)

Some of the complex nature and specifics of the Natrolite crystals:

Occurrences of Natrolite
Geological Setting: Cavities in amygdaloidal basalts

Physical Properties of Natrolite
Lustre: Vitreous, Pearly
Diaphaneity (Transparency): Transparent, Translucent
Colour: White, Colorless, Red, Yellow, Brown, Green, bluish
Streak: White
Hardness (Mohs): 5 - 5
Tenacity: Brittle
Cleavage: Perfect
on {110}
Parting: on {010}
Fracture: Irregular/Uneven
Density (measured): 2.2 - 2.26 g/cm3
Density (calculated): 2.25 g/cm3

Crystallography of Natrolite
Crystal System: Orthorhombic
Class (H-M): mm2 - Pyramidal
Space Group: Fdd2
Cell Parameters: a = 18.2930(2) , b = 18.6430(5) , c = 6.5860(5)
Ratio: a:b:c = 0.981 : 1 : 0.353
Unit Cell Volume: V 2,246.07 (Calculated from Unit Cell)
Z: 8
Morphology: Crystals short to long prismatic, up to 1 m in length.
Twinning: On {110}, {011}, {031}

Kindest regards,
Shauno.

Edited for spelling/grammar.
 
Heatho said:
Very interesting Shauno, those fibres look worse than asbestos.

Hi Heatho,

Almost. I think they are slightly heavier and less prone to getting airborne than the equivalent Asbestos fibres would be, and luckily so, as it's a wonderful crystal creation that's worthy of any mineral collection. I certainly wouldn't like to inhale any of it though lol.

I was just thinking that Natrolite is not unlike like a micro/miniature version of Mesolite. They must be of a similar structure and makeup. A nice Mesolite specimen is something else I'd love to get hold of one day. It's on the ever growing list lol.

Hope all has been well.
Kindest regards,
Shauno.
 

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