While the usual hue of this mineral is a dull greenish grey or white, occasional localities contain some different colours, including the peachy mauve found in this 9.6 x 5.9 x 2.9 cm specimen from a vug in the basalt trapps of New Jersey. Its habit is usually fibrous, with radial crystal aggregates. It was first discovered in the Italian Alps in 1828, and named from the Greek words for well put together since it resists being powdered. Despite this it ias a fragile mineral and can flake off easily when roughly handled.

It forms in a variety of ways, the main ones being in a kind of granitoid rock called a nepheline syenite, as hydrothermal alteration products in gas bubbles in basalt and in association with serpentine (metamorphosed mantle or volcanic rocks). While soft (4-5 on Mohs scale), it has been used in jewellery, particularly the lovely blue material from Hispaniola called Larimar that I will discuss in my next post. It is found in many places worldwide.


Image credit: Rob Lavinsky/
Effects of Alkaline Additives on the Thermal Behavior and Properties of Cameroonian Poorly Fluxing Clay Ceramics

Read the full paper at:

DOI: 10.4236/jmmce.2014.25049

Antoine Elimbi1*, Joseph M. Dika2, Chantale N. Djangang1

Ball clay and alkaline feldspars (syenite and nepheline syenite) were mixed with red kaolinite clay (rich in iron oxides but poor in fluxing oxides) and fired (1000°C - 1200°C) in order to improve certain characteristics of the obtained ceramics. eww140929gjr The thermal behavior of the mixtures was monitored via Young modulus whereas linear shrinkage, water absorption, bulk density, flexural strength, microstructure and crystalline phases of fired products were examined. In the case of red clay-ball clay mixtures, the amount of mullite or cristobalite increased with heating temperature and the amount of additive, whereas the temperature at which there is an important sintering decreased with the increase of additive. In the ceramics produced from the mixtures of red clay-alkaline additive, contrary to mullite, the amount of cristobalite decreased with both the amount of additive and heating temperature. Also in the data of Young modulus, there was a decrease of temperature assigned to the beginning of densification. Additionally, incorporating at least 15% of alkaline additive to red clay and heating between 1050°C and 1200°C leads to ceramics with low water absorption (0.70% to 0.25%). However when using the same amount of additive and heating the mixtures at the same temperature, ceramics produced from nepheline syenite were denser than those obtained from syenite. Addition of ball clay or alkaline feldspars to kaolinite clay containing great amount of iron oxides and low fluxing oxides allows getting compact ceramics at reduced temperature.

Clay, Syenite, Nepheline Syenite, Ceramics, Reduced Temperature

Mount Dromedary Cool Temperate Rainforest by Poytr on Flickr.

Andranondambo Sapphire Discovery ( Madagascar )

by Alain Darbellay GGGems

© 2012 A to izzard rights reserved.

Tranomaro in 1991 >>

Geodesic division
We intendment distinguish:
1 the volcanic solid mass of
Androy, it is covered with
thorny forest and meadows.

2 the gneissic zone in point of as far as
Mandrarean Androy, fields
plains and hills, rare zones
in point of savanna on as to yankee doodle ground At the time
calcareous elytron. of the great
Altitude varies there from pointlessness in
600 meters on the hills the south.
to 250 meters at the bottom.

3 the picture slope in relation to the occlusive Anosyans
chains which tops are staged between
1500 and 2000 meters. Yourself is a field of

Geological divisions.
1 Crystalline schists.
Gneiss including diopside, syenitic eysies
gneisses, arteritic injections, abyssal rock at
cordierite, etc.
2 Old prickly rocks.
Pegmatites, Dissogénites, Esirians
granites, charnockites, kalambatreans
granites, late granites.
3 Former emotional rocks.
(Bursting solid mass pertinent to Androy)
a) A the base, a thick basaltic
subhorizontale series.
b) Basaltic dykes. On the road to Andranondambo
c) A thick ahead subhorizontale rhyolitic series.
d) Rhyolitic dykes.
4 Recent formations.
If russet-red sands are excluded, the fore
formations overlook only a very weak digenesis.
Her is necessary to quote the alluvial plains of
Androtsy, Esira, Sangoria and Pisopiso.
A notable calcareous carapace covers most of the area.

Metamorphized dolomitic limestone.
Near Andranondambo

The anosyans granites are regarded as an instance synorogenes, eocambrians
formed good terms the androyans series in transit to which an age higher beside 2400 MY
is allotted.

The esirians granites present danged variable crushings of intensity which
often give top brass a gneissic facies.
There is sometimes passage till orthogneisses. General foliation is surrogate vertex.

The occurrences of the Andranondambo area were industrially exploited since 1993 and have been
nearly abandoned of small number years later. Actually, herself is very arduous to action sapphire direct in
mother rock, because corundum is not concentrated enough. Furthermore, the inflexibility with respect to the
rock makes its exploitation very expensive.


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About the Author


Alain Darbellay is the author of several novels seminal by his adventures researching one of the strangest natural wonders: Precious stone. His attractive trips newfashioned windfall producer countries similar Madagascar or Pakistan, often accompanied whereby his congenator brother, led Alain to also evulgation a filiation about articles on the subject.

Naturstein aus Russland

Gabbro ist ein schwarzer Gabbro aus Russland, Izerbelsky ist ein grauer Granit aus Russland, Kalguvara ist ein roter Orthogneis aus Russland, Kashina Gora ist ein grauer Granit aus Russland, Mansurovsky ist ein weißer Granit aus Russland, Maslovsky ist ein grüner Granit aus Russland, Moskovsky ist ein weißer Marmor aus Russland, Nebizhsky ist ein schwarzer Syenit aus Russland, Pushtulimsky ist…

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Voor ‘echte’ architecten zal het een gotspe zijn: een aannemer laten nabouwen wat je elders hebt gezien. Advocaat en senator Federico Rosazza deed het gewoon anderhalve eeuw geleden. Hij combineerde zijn ruime beurs met wat hij zag tijdens zijn vele buitenlandse reizen én het vakmanschap van de in zijn dal wonende steenhouwers. ’s Zomers werd het harde graniet uit de berg gewonnen; op de foto zie je de kraan van de laatste nog in gebruik zijnde groeve “Syenit”. Als je scherm groot genoeg is, kun je het hele verhaal uit de Duitse GTA-gids van Rother lezen. ’s Winters werden de vakmensen genodigd naar grote projecten als de kathedraal van New York of de dom van Milaan. Ik toon jullie hierboven een greep uit de verscheidenheid aan bouwstijlen die Rosazza uit Schotland, Toscane, Wallis, Lombardije liet nabouwen. Hij liet ook een 300 meter lange tunnel “Galleria di Rosazza” bouwen om het Cervo-dal met Oropa te verbinden en daarmee de weg naar Biella sterk te verkorten.

Bij de laatste twee foto’s: als het dak het niet meer houdt, is het hele huis verloren. Deze brug bij Piedicavallo houdt het nog wel een tijdje.