Crystalline Gold with Arsenopyrite in Quartz — Sixteen-to-One Mine, Alleghany, California (~114 Ma):

The legendary Original Sixteen-to-One Mine, located in the historic town of Alleghany in Sierra County, California. It is world-famous among collectors for producing some of the finest jewelry-grade crystalline gold in quartz ever found. 

These deposits form throughout Earth's history when mineral-rich, superheated fluids circulate through fault zones and precipitate gold alongside sulfides.

The specimen is composed of three distinct mineral phases, each with its own chemical makeup.

Native Gold (Au): 
The bright yellow, malleable metal. At the Sixteen-to-One Mine, this gold is exceptionally high-purity, typically consisting of roughly 80% to 90% pure gold alloyed with 10% to 20% silver (electrum).

Arsenopyrite (FeAsS): 
The metallic, silver-gray to steel-gray crystals. It is an iron arsenic sulfide made of equal parts iron, arsenic, and sulfur.

Quartz (SiO₂):
The white, translucent matrix surrounding the gold. It is a crystalline network made of silicon and oxygen (silicon dioxide).

• Rock Type: Hydrothermal Quartz Vein (Orogenic Lode Deposit)
• Category: Metamorphic/Hydrothermal Rock [1]

• Major Matrix (90%–98%): Quartz (SiO₂) — The primary host rock.
• Minor Sulfides (1%–5%): Arsenopyrite (FeAsS) — The silver-metallic crystals.
• Native Gold (Au) — The yellow crystalline veins/pockets.

• Primary Rock: Quartz vein
• Metallic Minerals: Arsenopyrite, Native Gold (Electrum)
• Chemical Elements: Silicon, Oxygen, Iron, Arsenic, Sulfur, Gold, Silver

Geological Specifications:

Geological Era: Mesozoic Era 
Geological Period: Early Cretaceous Period
Absolute Age: Approximately 114 million years old.
Tectonic Event: The mineralization formed during the Nevadan/Sierran Orogeny, a major mountain-building event where tectonic plate collisions forced superheated, gold-bearing fluids up into fault lines, forming rich "pockets" of quartz, gold, and arsenopyrite.

1. Safety Protocols:

(Essential)Wear Gloves:
Always use disposable gloves when handling the raw specimen to avoid absorbing traces of arsenic through your skin.

Wash Hands:
Thoroughly clean your hands with soap and warm water if you touch the rock directly.

Never Heat or Crush: 
Grinding, smashing, or heating arsenopyrite releases highly toxic, dangerous arsenic gas that smells like garlic.

2. Gentle Cleaning Methods:
Because gold is soft and arsenopyrite can degrade, avoid aggressive chemical acids (like nitric acid) or ultrasonic cleaners, which can shatter delicate crystalline gold structures.

Water and Soap Wash:
Soak the specimen briefly in a lukewarm, mild soap solution

Brush Carefully:
Use a soft-bristled toothbrush to gently scrub away surface dirt or loose clay from the quartz pockets.

Dry Thoroughly:
Moisture is the enemy of sulfide minerals. Pat it dry with a towel immediately after washing, or use a hair dryer on a cool/no-heat setting to dry inside tight quartz crevices.

3. Proper Storage & Display:

Control Humidity:
Store the piece in a dry environment. High humidity triggers oxidation, which causes arsenopyrite to lose its metallic luster and tarnish into iridescent pink, brown, or copper colors.

Use Silica Gel:
Place a small packet of silica gel inside its display case or storage box to absorb any ambient moisture.

Keep Out of Direct Sunlight:
Intense sunlight and heat accelerate the breakdown of sulfides, potentially creating a hazardous white powder coating called arsenolite.

Store Separately: 
Do not let the specimen rub or bump against other rocks in your collection. Keep it separated in its own individual box to protect the fragile gold crystals from bending or snapping.

Crystalline Gold in Quartz (with Arsenopyrite)
Sixteen-to-One Mine, 
Alleghany, California
Mesozoic Era (Cretaceous) — ~114 Ma

Mined from California's historic Sixteen-to-One Mine, this specimen showcases the stunning contrast of natural crystalline gold and silver-grey arsenopyrite inside a quartz pocket. These rich "pockets" were deposited over 110 million years ago when tectonic collisions forced superheated, mineral-rich fluids up into the Sierra Nevada mountain faults.

SPECIFICATIONS

Premium Crystalline Gold with Arsenopyrite in Quartz

Locality: Original Sixteen-to-One Mine, Alleghany, Sierra County, California, USA
Geological Era: Mesozoic Era (Early Cretaceous Period, ~114 Million Years Old)

Specimen Details:
Matrix: Translucent to white vein quartz.

Inclusions:  Bright, high-purity crystalline native gold intergrown with metallic, silver-gray arsenopyrite crystals. 

Significance: Sourced from California's most famous underground lode gold mine, renowned for producing world-class jewelry-grade specimens.

Note: Arsenopyrite contains iron, sulfur, and arsenic. Handle with care, wash hands after handling, and display safely away from high heat or moisture.*

Size/Dimensions:  1.5" x 1.5" x 1"inch

Weight:: 27g