#acicular

[mymineralbox]

Bismuthinite — Bi₂S₃ — is the principal ore of bismuth and one of the most unusual sulfide minerals in any collection. This specimen comes from Inner Mongolia, where acicular (needle-like) crystals form in hydrothermal veins cutting through granite and skarn rocks.

What makes bismuthinite special:

• Silvery-gray to tin-white metallic luster that tarnishes to iridescent bronze over time

• Perfect cleavage in one direction — splits into fine blades

• Softer than most sulfides (Mohs 2) — can scratch with a fingernail

• The densest common sulfide (bismuth is a heavy metal atom)

• Produces bismuth metal — used in pharmaceuticals (Pepto-Bismol), solders, and the famous iridescent hopper crystals grown by collectors

Bismuth itself is fascinating — its nucleus was long believed stable, but in 2003 physicists discovered it’s actually weakly radioactive with a half-life longer than the age of the universe. So every bismuthinite crystal is, very slowly, becoming thallium.

[spiritheyregone]

Bushes of acicular aragonite crystals, also known as frostwork. (The Virtual Cave)

[earthstory]

Two generations of Brochantite, one atop the other

Many of us have grown similar crystals by hanging a piece of string into a copper sulphate solution and letting it evaporate. In nature, an arid climate and an oxidising (see http://bit.ly/1I4XWKt for an explanation) copper sulphide deposit are required for this mineral, which forms when groundwater interacts with reduced ore deposits changing the primary minerals to secondary ones. Preservation is also an issue since like Atacamite, another arid mineral (see http://bit.ly/2iEOVFX), it is soluble in water and so is only rarely found.

Colour ranges from bright emerald green to a dark blue green, though its softness (3.5 on Mohs scale) prevents faceting or jewellery use. Since it forms in the same environments as malachite and azurite (copper carbonates), they are frequently found together, and sometime brochantite replaces the other minerals, taking on their crystal shape in a process called pseudomorphism (from pretend shape in Greek). The more usual distinguishing shape is as sprays of acicular (needle shaped) crystals, often radiating from a common centre. It was named in 1824 after a French mineralogist, Brochant de Villiers, and is an important ore mineral in several desert mines.

Main localities include the copper mines of the Atacama desert in Chile, the Zaire copper belt in the Democratic Republic of Congo, the Tsumeb mine (see http://bit.ly/1c2CjkD) and Arizona in the USA. A few stunning specimens (including the one in the photo that resembles an eerie mineral trilobite that once prowled over some long vanished Cambrian sea) have emerged this past decade from the Milpillas mine in Sonora, Mexico, also famous for beautiful azurites. Here, in this 2.4 x 1.8 x 1.8 cm thumbnail several deep green crystals rise above sprays of needle shaped (called acicular) light green material making for a stunning ensemble.

Loz

Image credit: Rob Lavinsky/iRocks.com http://www.mindat.org/min-779.html http://www.galleries.com/Brochantite http://bit.ly/1N0Tqox http://bit.ly/20pv7TD

[spiritheyregone]

A common progression from calcite to aragonite due to evaporative enrichment, where a nodular mass of calcite popcorn is tipped by sprays of aragonite needles. (The Virtual Cave)

[biology-geology-beaches-india]

So fine, so straight, so sharp, so needle-like and so thickly clustered were the teeth in the decapitated head of this fish that they almost formed a fine fuzz!!! The pain felt by prey when those jaws snapped shut with full force can only be imagined!!!

This head - the beast almost snarling in death - came from the discards of fishing nets. Whether the fisherman had lopped off the more edible lower body of this fish I do not know.

A short distance north of the confluence of the Gosthani River. May 10, 2010. Bheemili, Andhra Pradesh.

[unearthedgemstones]

Acicular crystal spikes

[lookto-thecosmos]

I was tagged!!

I was tagged by skeletalflowergirl Name a band and then answer the questions with songs. Band: Aerosmith Your gender: Woman of the World How do you feel: Girl Keeps Coming Apart Where do you live: Red House If you could go anywhere, where?: Hollywood Your best friend is: Sight for Sore Eyes Weather: Girls of Summer Favorite time of day: Oasis in the Night If your life was a tv show what would be the title: Don't Get Mad, Get Even What is life to you: Ain't That A Bitch Your relationship: Falling In Love (Is Hard On The Knees) Your fear: Another Last Goodbye Dreams: Kiss Your Past Goodbye I tag: acicular kurapiak blanktaehyeong arsenic-milkshake involuntary-hipster mayan-warrior s-o-u-p-ernatural suzuyajuuzou-and-kagehina Basically if any of my followers want to do this you can do it and say I tagged you! Thanks for tagging me skeletalflowergirl

[tandytoaster]

stand by me, lapis, cats, mono, and toaster :0

That's literally all there is to know about me omg