How do I identify Gordaite?

Gordaite can be identified by its hardness of 2.5 on the Mohs scale, Colourless color. Look for these key characteristics when examining specimens.

What color is Gordaite?

Gordaite typically appears in Colourless, pale bluish, pale greenish. Color can vary depending on impurities and formation conditions.

How hard is Gordaite?

Gordaite has a hardness of 2.5 on the Mohs scale. This makes it a soft mineral that can be scratched easily.

Gordaite

A variety of Minerals

What is Gordaite?

Gordaite is a sulfate mineral composed primarily of hydrous zinc sodium sulfate chloride hydroxide with formula: NaZn4(SO4)(OH)6Cl·6H2O. It was named for the discovery location in the Sierra Gorda district of Chile. Gordaite forms as tabular trigonal crystals. Gordaite first appeared after a research dive in September 1984 from the Juan de Fuca Ridge of the northeastern side of the Pacific Ocean. Gordaite was also described from weathered slag deposits as a result of copper smelting in Hettstedt, Germany. The mineral exhibits a hexagonal shape with clear or white (green if cuprian – Cu) crystals ranging from planar to broad habit and has a point group of 3. Gordaite commonly occurs near minerals such as sphalerite, boleite and gypsum. The most recent finding occurred in the San Francisco mine in Chile where copper-zinc sulfide deposits were found.

Gordaite Market Value Calculator

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Gordaite Localities Map

See where Gordaite is found with a localities map, collecting zones, and geology context. Generate a sample map preview below.

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North ZoneCentral RidgeSouth Basin

Key Characteristics

Characteristics of Gordaite

Gordaite belongs to the point group P3. This indicates that the mineral has a primitive lattice and belongs to the hexagonal/trigonal point group. Gordaite crystals are typically white or opaque and can sometimes exhibit a greenish color if trace copper is present. The crystals are broad and flat and have a vitreous luster. The mineral shows a cleavage plain parallel to {0001}, is flexible and has a Mohs hardness of about 2.5. The measured specific gravity is about 2.627 whereas the calculated value is about 2.640. Its crystallographic axes are a = 8.3556 and c = 13.025 angstroms, similar to that is the sample from Germany.

Composition of Gordaite

The 1998 Nasdala article examines the ALV 1457-5R sample found on the sea floor of the Juan de Fuca Ridge. The sample itself was taken from a sulfide chimney with mass of about 2.5 kg. The chimney was composed of about 98% permeable sulfides and 2% sulfates. The sulfides were primarily composed of iron sulfides such as pyrite and sphalerite and were present in the core of the chimney. The sulfate portions were found in concentric layers on the outside of the sample, alternating between [Zn4(OH)6(SO4)Cl]- and [Na(H2O)6]- interlayers. Table 1: Chemical Composition of the Gordaite Mineral (1) San Francisco mine, Chile; by electron microprobe, H2O by CHN analyzer; low analytical total due to loss of H2O during grinding, Na too high due to peak overlaps with Zn; after adjusting Na2O to 5.5% from AA, and partitioning H between H2O and (OH)- according to crystal-structure analysis, corresponds to Na1.54Zn3.39(S04)(OH)6Cl0.95·6H20. (2) NaZn4(SO4)(OH)6Cl·6H20. Table 1 is taken from a study done based on the findings in the San Francisco mine. Section 1 displays the results based from an electron microprobe test which resulted in loss of water. Section 2 displays the normalized results taken from crystal structure analysis. Recognition of gordaite crystals is problematic due to its association with tabular baryte. Based on the findings of the dive at Juan de Fuca Ridge, gordaite was formed due to the reaction of discharging hydrothermal fluids with sea water. The overwhelming presence of baryte crystals confirms the idea that gordaite must be more than a byproduct of weathering.