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Formula: KAl7(NO3)4(OH)16Cl2.8H2O
Nitrate
Crystal System: Monoclinic
Specific gravity: 2.0 measured, 2.185 calculated for the ideal formula
Hardness: 1
Streak: White
Colour: White, colourless
Solubility: Completely soluble in hydrochloric and sulphuric acids, and dissolves with difficulty in nitric acid.
Gelatinous when moist. Highly hygroscopic, forming a residue of Al(OH)3
Environments
Localities
At an unspecified sveite occurrence in the San Joaquin Valley, San Joaquin county, California, USA,
sveite occurs on the ceiling of an overhanging ledge of vitric
rhyolitic tuff that caps
a low hill. The sveite is white and lumpy, and has a gelatinous consistency when moist. The mean annual
precipitation is about 360 mm, occurring as rain, mostly during November to April; less than 10 mm of rain falls
during the summer, June to September. Maximum temperatures can reach 45oC in the summer and minimum
temperatures rarely drop as far as –5oC in the winter.
The sveite occurrence is on the north face of a small hill and never receives direct sunlight due to the
overhanging ledge. During wet periods water percolates through the soil and the
tuff and drips from the ceiling of the overhang where the sveite
precipitates. A thin (up to 15 cm) soil layer mantles the flat top of the hill above the sveite location. A
sparse cover of annual grasses and moss grows on the soil. Bird faeces and feathers were collected from the soil
above the overhanging ledge under which the sveite precipitated.
Sveite occurs as a white, curd-like aggregation of submicroscopic crystals. Lumps of sveite pulled
from the rock surface have smooth interior cavities. The crystals are small and platy with rectangular shapes that
are less than 2 microns long and 0.05 microns thick
(CM 59.2.409–421).
At the type locality, the Cerro Autana Cave, Amazonas, Venezuela, the Cave in which sveite occurs is located
in the precipitous cliff face of an 850 metre high pinnacle, the Cerro Autana. Its entrances are three quarters the
way up from the base of the cliff and were reached for the first time in 1971 from the top of the Cerro, where the
exploration team landed by helicopter. The pinnacle is an outlier of Precambrian (4,600 to 541 million years ago)
pink quartzite, forming very thick horizontal strata resting
disconformably on a granitic basement. The cave itself is composed of
several entrances interconnected by passages and large chambers. It probably formed by initial weathering of
quartzite producing soft material along joints and bedding planes,
followed by mechanical removal of sand by running water.
On the walls of a vast chamber, sveite forms white crusts and efflorescences which obviously have been
deposited by solutions trickling from a bedding plane close to the ceiling. It is generally believed that nitrate
minerals in caves form from animal excreta like bat guano. In the case of sveite found here, however, the
mineral has obviously been deposited by solutions trickling directly from the ceiling of the cave. As there is
probably no other cave at a higher level, it seems that nitrate and chloride must have been provided by rain water
and by the organic matter contained in the soil of the top of the Cerro Autana. The solutions dissolve aluminium and
potassium from feldspar and
mica contained in minor amounts in the
quartzite. As the solutions are very diluted, the deposition of
sveite can be achieved only after considerable evaporation
(Transactions of the Geological Society of South Africa 83.239-241).
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