I'm selling this totally natural, raw, gorgeous, clear selenite crystal slab. Selenite is one of the most popular stones for crystal healing. It is also just gorgeous and perfect for any gem and mineral collection.
This specimen is 100% natural. It has not been altered in anyway.
This type of selenite or crystallized gypsum is called windowpane selenite of water clear selenite. This is a really clear piece - is looks like flawless glass in some areas which is interesting because this type of selenite used to be used as windows in old mining towns in America a long long time ago. I suspect that is where they acquired the name ' window pane selenite ' large mica sheets also used to be used a windows in old mining towns. There are some really well preserved ghost towns that still have these interesting mineral sheets in the window frames still.
To get ahold of a piece THIS CLEAR is very unusual. This piece is really remarkable and I really want to keep it. But I have to let go of some stuff to raise some money for some dental work. I am sure it will find a good home out there and make someone else really happy.
I got this gorgeous piece at the Tucson gem and mineral show. I found some really amazing treasures there.
This piece is really nice and really large and is from Utah, USA.
This particular specimen weighs 411.10 carats which is the same as 82.22 grams, which is also 2.91 ounces.
And it measures 156 mm by 98 mm by 6 mm thick. It's 156mm long which is the same as 6 1/2 inches and is very gorgeous! It is worth noting that this a 100% totally natural piece.
This particular kind of selenite is the rarest form.
There are several reasons why it is popular for crystal healers and I've put all that info below with the Wikipedia article about this Mineral.
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Selenite is one of the most powerful stones of the New Age. It brings light into the energetic bodies and instantly clears all chakras. It is one of the few stones that does not ever need to be cleansed. It can be used to cleanse other stones as well. Katrina Raphaell, in her Crystal Trilogy writes extensively about the benefits of using selenite in crystal healing, and in The Crystalline Transmission states that this crystal is endowed with a special ability to alter the very nature of physical matter. Judy Hall, in her latest book, 101 Power Crystals, The Ultimate Guide to Magical Crystals,Gems, and Stones for Healing and Transformation, states "Selenite stands at the threshold between spirit and matter". A Kabbalistic creation myth tells us that before the universe existed, God was everywhere, but he had to inhale to create space for our world. Realizing he was not present in creation, he fashioned vessels of divine light to populate the universe, but they shattered. Carrying that light, Selenite's task is to reunite the shards of the divine with their source. Relative to Transformational Power, she states that "Selenite accesses angelic consciousness and brings divine light into everything it touches" and "It also facilitates female rites of passage, such as puberty and menopause, encouraging reconnection to the wise feminine divine power." She recommends to re-empower [selenite] in moonlight.We recommend recharging it in sunlight periodically for short periods.
Selenite (mineral)
Not to be confused with Selenite (ion).
Selenite, satin spar, desert rose, and gypsum flower are four varieties of the mineral gypsum; all four varieties show obvious crystalline structure. The four "crystalline" varieties of gypsum are sometimes grouped together and called selenite.
Selenite
Category
Sulfate mineral
Formula
(repeating unit)
CaSO4·2H2O
Crystal system
Monoclinic (2/m) Space Group: A2/a
Identification
Formula mass
172.17
Color
Brown green, Brownish yellow, Greenish, Gray green, Gray white
Crystal habit
Earthy – Dull, clay-like texture with no visible crystalline affinities, (e.g. howlite).
Cleavage
[010] Perfect, [100] Distinct, [011] Distinct
Fracture
Fibrous – Thin, elongated fractures produced by crystal forms or intersecting cleavages (e.g. asbestos).
Mohs scale hardness
2
Luster
Pearly
Streak
white
Specific gravity
2.9
Optical properties
Biaxial (-) 2V=58
Refractive index
nα=1.519-1.521, nβ=1.522-1.523, nγ=1.529-1.53
Birefringence
δ =0.0090-0.0100
Other characteristics
non-radioactive, non-magnetic, Fluorescent.
References
[1]
All varieties of gypsum, including selenite and alabaster, are composed of calcium sulfatedihydrate (meaning that it has two molecules of water), with the chemical formula CaSO4·2H2O. Selenite contains no significant selenium; the similarity of names comes from both substances being named from the Ancient Greek word for the Moon.
Some of the largest crystals ever found are selenite crystals – the largest specimen found in the Naica Mine's Cave of the Crystals is 12 metres long and weighs 55 tons.
History and etymology
The etymology of selenite is through Middle English selinete, from Latin selenites, from Greek selēnitēs (lithos), literally, moonstone or stone of the moon, from selēnē (Moon). The ancients had a belief that certain transparent crystals waxed and waned with the moon. From the 15th century, "selenite" has referred specifically to the variety of gypsum that occurs in transparent crystals or crystalline masses.[2]
Identification of crystals as gypsum
All varieties of gypsum are very soft minerals(hardness: 2 on Mohs Scale). This is the most important identifying characteristic of gypsum, as any variety of gypsum can be easily scratched with a fingernail. Also, because gypsum has natural thermal insulating properties, all varieties feel cold to the touch.
Varieties
Though sometimes grouped together as "selenite", the four crystalline varieties have differences. General identifying descriptions of the related crystalline varieties are:
Selenite
* most often transparent and colorless: it is named after Greek σεληνη "the moon".
* if selenite crystals show translucency, opacity, and/or color, it is caused by the presence of other minerals, sometimes in druse
* druse is the crust of tiny, minute, or micro crystals that form or fuse either within or upon the surface of a rock vug, geode, or another crystal
Satin spar
* most often silky, fibrous, and translucent (pearly, milky); can exhibit some coloration
* the satin spar name can also be applied to fibrous calcite (a related calcium mineral) – calcite is a harder mineral – and feels greasier, waxier, or oilier to the touch.
Desert rose
* rosette shaped gypsum with outer druse of sand or with sand throughout – most often sand colored (in all the colors that sand can exhibit)
* the desert rose name can also be applied to barite desert roses (another related sulfate mineral) – barite is a harder mineral with higher density
Gypsum flower
* rosette shaped gypsum with spreading fibers – can include outer druse
* the difference between desert roses and gypsum flowers is that desert roses look like roses, whereas gypsum flowers form a myriad of shapes
Use and history
Varieties of gypsum known as "satin spar" and "alabaster" are used for a variety of ornamental purposes.[3] But also because of the long history of the commercial value and use of both gypsum and alabaster, the four crystalline varieties have been somewhat ignored, except as a curiosity or as rock collectibles (not commonly used).
Crystal habit refers to the shapes that crystals exhibit.[4]
Selenite crystals commonly occur as tabular, reticular, and columnar crystals, often with no imperfections or inclusions, and thereby can appear water or glass-like. Many collectible selenite crystals have interesting inclusions such as, accompanying related minerals, interior druse, dendrites, and fossils. In some rare instances, water was encased as a fluid inclusion when the crystal formed (see Peñoles Mine reference in external links).
Selenite crystals sometimes form in thin tabular or mica-like sheets and have been used as glass panes[5][6] as at Santa Sabina in Rome.
Selenite crystals sometimes will also exhibit bladed rosette habit (usually transparent and like desert roses) often with accompanying transparent, columnar crystals. Selenite crystals can be found both attached to a matrix or base rock, but can commonly be found as entire free-floating crystals, often in clay beds (and as can desert roses).
Satin spar is almost always prismatic and fibrous in a parallel crystal habit. Satin spar often occurs in seams, some of them quite long, and is often attached to a matrix or base rock.
Desert roses are most often bladed, exhibiting the familiar shape of a rose, and almost always have an exterior druse. Desert roses are almost always unattached to a matrix or base rock.
Gypsum flowers are most often acicular, scaly, stellate, and lenticular. Gypsum flowers most often exhibit simple twinning (known as contact twins); where parallel, long, needle-like crystals, sometimes having severe curves and bends, will frequently form “ram’s horns”, "fishtail", "arrow/spear-head", and "swallowtail" twins. Selenite crystals can also exhibit “arrow/spear-head” as well as “duck-bill” twins. Both selenite crystals and gypsum flowers sometimes form quite densely in acicular mats or nets; and can be quite brittle and fragile. Gypsum flowers are usually attached to a matrix (can be gypsum) or base rock.
Color
Gypsum crystals are colorless (most often selenite), white (or pearly – most often satin spar), gray, brown, beige, orange, pink, yellow, light red, and green. Colors are caused by the presence of other mineral inclusions such as, copper ores, sulfur and sulfides, silver, ironores, coal, calcite, dolomite, and opal.
Transparency
Gypsum crystals can be transparent (most often selenite), translucent (most often satin spar but also selenite and gypsum flowers), and opaque (most often the rosettes and flowers). Opacity can be caused by impurities, inclusions, druse, and crust, and can occur in all four crystalline varieties.
Luster
Both selenite and satin spar are often glassy or vitreous, pearly, and silky – especially on cleavage surfaces. Luster is not often exhibited in the rosettes, due to their exterior druse; nevertheless, the rosettes often show glassy to pearly luster on edges. Gypsum flowers usually exhibit more luster than desert roses.
Play of color
Fibrous satin spar exhibits chatoyancy (cat’s eye effect).
When cut across the fibers and polished on the ends, satin spar exhibits an optical illusionwhen placed on a printed or pictured surface: print and pictures appear to be on the surface of the sample. It is often called and sold as the “television stone” (as is ulexite).[7]
Some selenite and satin spar specimens exhibit fluorescence or phosphorescence.
Tenacity
All four crystalline varieties are slightly flexible, though will break if bent significantly. They are not elastic, meaning they can be bent, but will not bend back on their own.
All four crystalline varieties are sectile in that they can be easily cut, will peel (particularly selenite crystals that exhibit mica-like properties), and like all gypsum varieties, can be scratched by a fingernail (hardness: 2 on Mohs Scale). The rosettes are not quite as soft due to their exterior druse; nevertheless, they too can be scratched.
Selenite crystals that exhibit in either reticular or acicular habits, satin spar, in general (as fibrous crystals are thin and narrow), desert roses that are thinly bladed, and gypsum flowers, particularly acicular gypsum flowers, can be quite brittle and easily broken.
Gypsum occurs on every continent and is the most common of all the sulfate minerals.
Gypsum is formed as an evaporative mineral, frequently found in alkaline lake muds, clay beds, evaporated seas, salt flats, salt springs, and caves. Gypsum, also, is frequently found in conjunction with other minerals such as, copper ores, sulfur and sulfides, silver, iron ores, coal, calcite, dolomite, limestone, and opal. Gypsum has been dated to almost every geologic age since the Silurian Period 443.7 ± 1.5 Ma.[9]
In dry, desert conditions and arid areas, sand may become trapped both on the inside and the outside of gypsum crystals as they form. Interior inclusion of sand can take on shapes such as an interior hourglass shape common to selenite crystals of the ancient Great Salt Plains Lake bed, Oklahoma, US.[10] Exterior inclusion (druse) occurs as embedded sand grains on the surface such as, commonly seen in the familiar desert rose.
When gypsum dehydrates severely, anhydrite is formed. If water is reintroduced, gypsum can and will reform – including as the four crystalline varieties. An example of gypsum crystals reforming in modern times is found at Philips Copper Mine (closed and abandoned), Putnam County, New York, US where selenite micro crystal coatings are commonly found on numerous surfaces (rock and otherwise) in the cave and in the dump.[11]
Whereas geology, mineralogy, and rockhounding groups, clubs, and societies as well as museums usually date (of find and geologic), photograph, and note location of minerals, much of the retail mineral and jewellery trade can be somewhat casual about dates, locations, and descriptive claims.
Gypsum
From Wikipedia, the free encyclopedia
This article is about the mineral. For other uses, see Gypsum (disambiguation).
Gypsum
Gips - Lubin, Poland..jpg
General
Category Sulfate minerals
Formula
(repeating unit) CaSO4·2H2O
Strunz classification 7.CD.40
Crystal system Monoclinic
Crystal class Prismatic (2/m)
H-M symbol: (2/m)
Space group Monoclinic
Space group: I2/a
Unit cell a = 5.679(5), b = 15.202(14)
c = 6.522(6) [Å]; β = 118.43°; Z = 4
Identification
Color Colorless to white; may be yellow, tan, blue, pink, brown, reddish brown or gray due to impurities
Crystal habit Massive, flat. Elongated and generally prismatic crystals
Twinning Very common on {110}
Cleavage Perfect on {010}, distinct on {100}
Fracture Conchoidal on {100}, splintery parallel to [001]
Tenacity Flexible, inelastic
Mohs scale hardness 1.5–2 (defining mineral for 2)
Luster Vitreous to silky, pearly, or waxy
Streak White
Diaphaneity Transparent to translucent
Specific gravity 2.31–2.33
Optical properties Biaxial (+)
Refractive index nα = 1.519–1.521
nβ = 1.522–1.523
nγ = 1.529–1.530
Birefringence δ = 0.010
Pleochroism None
2V angle 58°
Fusibility 5
Solubility Hot, dilute HCl
References [1][2][3]
Major varieties
Satin spar Pearly, fibrous masses
Selenite Transparent and bladed crystals
Alabaster Fine-grained, slightly colored
Gypsum is a soft sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula CaSO4·2H2O.[3] It is widely mined and is used as a fertilizer, and as the main constituent in many forms of plaster, blackboard chalk and wallboard. A massive fine-grained white or lightly tinted variety of gypsum, called alabaster, has been used for sculpture by many cultures including Ancient Egypt, Mesopotamia, Ancient Rome, the Byzantine Empire and the Nottingham alabasters of Medieval England. Mohs scale of mineral hardness, based on scratch Hardness comparison, defines hardness value 2 as gypsum. It forms as an evaporite mineral and as a hydration product of anhydrite.
Contents [hide]
1 Etymology and history
2 Physical properties
3 Crystal varieties
4 Occurrence
5 Mining
6 Synthesis
7 Occupational safety
7.1 United States
8 Uses
9 Gallery
10 See also
11 References
12 External links
Etymology and history[edit]
The word gypsum is derived from the Greek word γύψος (gypsos), "plaster".[4] Because the quarries of the Montmartre district of Paris have long furnished burnt gypsum (calcined gypsum) used for various purposes, this dehydrated gypsum became known as plaster of Paris. Upon addition of water, after a few tens of minutes plaster of Paris becomes regular gypsum (dihydrate) again, causing the material to harden or "set" in ways that are useful for casting and construction.
Gypsum was known in Old English as spærstān, "spear stone", referring to its crystalline projections. (Thus, the word spar in mineralogy is by way of comparison to gypsum, referring to any non-ore mineral or crystal that forms in spearlike projections). Gypsum may act as a source of sulfur for plant growth, which was discovered by J. M. Mayer, and in the early 19th century, it was regarded as an almost miraculous fertilizer. American farmers were so anxious to acquire it that a lively smuggling trade with Nova Scotia evolved, resulting in the so-called "Plaster War" of 1820.[5] In the 19th century, it was also known as lime sulfate or sulfate of lime.
Physical properties[edit]
Gypsum crystals are plastic enough to bend under pressure of the hand. Sample on display at Musée cantonal de géologie de Lausanne.
Gypsum is moderately water-soluble (~2.0–2.5 g/l at 25 °C)[6] and, in contrast to most other salts, it exhibits retrograde solubility, becoming less soluble at higher temperatures. When gypsum is heated in air it loses water and converts first to calcium sulfate hemihydrate, (bassanite, often simply called "plaster") and, if heated further, to anhydrous calcium sulfate (anhydrite). As for anhydrite, its solubility in saline solutions and in brines is also strongly dependent on NaCl (common table salt) concentration.[6]
Gypsum crystals are found to contain anion water and hydrogen bonding.[7]
Crystal varieties[edit]
Main article: Selenite (mineral)
Gypsum occurs in nature as flattened and often twinned crystals, and transparent, cleavable masses called selenite. Selenite contains no significant selenium; rather, both substances were named for the ancient Greek word for the Moon.
Selenite may also occur in a silky, fibrous form, in which case it is commonly called "satin spar". Finally, it may also be granular or quite compact. In hand-sized samples, it can be anywhere from transparent to opaque. A very fine-grained white or lightly tinted variety of gypsum, called alabaster, is prized for ornamental work of various sorts. In arid areas, gypsum can occur in a flower-like form, typically opaque, with embedded sand grains called desert rose. It also forms some of the largest crystals found in nature, up to 12 m (39 ft) long, in the form of selenite.[8]
Occurrence[edit]
Gypsum is a common mineral, with thick and extensive evaporite beds in association with sedimentary rocks. Deposits are known to occur in strata from as far back as the Archaean eon.[9] Gypsum is deposited from lake and sea water, as well as in hot springs, from volcanic vapors, and sulfate solutions in veins. Hydrothermal anhydrite in veins is commonly hydrated to gypsum by groundwater in near-surface exposures. It is often associated with the minerals halite and sulfur. Gypsum is the most common sulfate mineral.[10] Pure gypsum is white, but other substances found as impurities may give a wide range of colors to local deposits.
Because gypsum dissolves over time in water, gypsum is rarely found in the form of sand. However, the unique conditions of the White Sands National Monument in the US state of New Mexico have created a 710 km2 (270 sq mi) expanse of white gypsum sand, enough to supply the construction industry with drywall for 1,000 years.[11] Commercial exploitation of the area, strongly opposed by area residents, was permanently prevented in 1933 when president Herbert Hoover declared the gypsum dunes a protected national monument.
Gypsum is also formed as a by-product of sulfide oxidation, amongst others by pyrite oxidation, when the sulfuric acid generated reacts with calcium carbonate. Its presence indicates oxidizing conditions. Under reducing conditions, the sulfates it contains can be reduced back to sulfide by sulfate-reducing bacteria. Electric power stations burning coal with flue gas desulfurization produce large quantities of gypsum as a byproduct from the scrubbers.
Orbital pictures from the Mars Reconnaissance Orbiter (MRO) have indicated the existence of gypsum dunes in the northern polar region of Mars,[12] which were later confirmed at ground level by the Mars Exploration Rover (MER) Opportunity.[13]
Gypsum crystals in the Cave of the Crystals in Mexico. Note person for scale
Veins of gypsum in the silts/marls of the Tea Green and Grey Marls, Blue Anchor, Somerset, UK
Veins of gypsum in Caprock Canyons State Park, Texas
Mining[edit]
Estimated production of Gypsum in 2015
(thousand metric tons)[14]
Country Production Reserves
China 132,000 N/A
Iran 22,000 1,600
Thailand 12,500 N/A
USA 11,500 700,000
Turkey 10,000 N/A
Spain 6,400 N/A
Mexico 5,300 N/A
Japan 5,000 N/A
Russia 4,500 N/A
Italy 4,100 N/A
India 3,500 39,000
Australia 3,500 N/A
Oman 3,500 N/A
Brazil 3,300 290,000
France 3,300 N/A
Canada 2,700 450,000
Saudi Arabia 2,400 N/A
Algeria 2,200 N/A
Germany 1,800 450,000
Argentina 1,400 N/A
Pakistan 1,300 N/A
United Kingdom 1,200 55,000
Other countries 15,000 N/A
World total 258,000 N/A
Commercial quantities of gypsum are found in the cities of Araripina and Grajaú in Brazil; in Pakistan, Jamaica, Iran (world's second largest producer), Thailand, Spain (the main producer in Europe), Germany, Italy, England, Ireland, Canada[15] and the United States. Large open pit quarries are located in many places including Plaster City, California, United States, and East Kutai, Kalimantan, Indonesia. Several small mines also exist in places such as Kalannie in Western Australia, where gypsum is sold to private buyers for additions of calcium and sulfur as well as reduction of aluminum toxicities on soil for agricultural purposes.
Crystals of gypsum up to 11 m (36 ft) long have been found in the caves of the Naica Mine of Chihuahua, Mexico. The crystals thrived in the cave's extremely rare and stable natural environment. Temperatures stayed at 58 °C (136 °F), and the cave was filled with mineral-rich water that drove the crystals' growth. The largest of those crystals weighs 55 tons and is around 500,000 years old.[16]
Golden gypsum crystals from Winnipeg
Gypsum sand from White Sands National Monument, New Mexico
Synthesis[edit]
Synthetic gypsum is recovered via flue-gas desulfurization at some coal-fired power plants. It can be used interchangeably with natural gypsum in some applications.
Gypsum also precipitates onto brackish water membranes, a phenomenon known as mineral salt scaling, such as during brackish water desalination of water with high concentrations of calcium and sulfate. Scaling decreases membrane life and productivity. This is one of the main obstacles in brackish water membrane desalination processes, such as reverse osmosis or nanofiltration. Other forms of scaling, such as calcite scaling, depending on the water source, can also be important considerations in distillation, as well as in heat exchangers, where either the salt solubility or concentration can change rapidly.
A new study has suggested that the formation of gypsum starts as tiny crystals of a mineral called bassanite (CaSO4·0.5H2O).[17] This process occurs via a three-stage pathway:
homogeneous nucleation of nanocrystalline bassanite;
self-assembly of bassanite into aggregates, and
transformation of bassanite into gypsum.
Occupational safety[edit]
People can be exposed to gypsum in the workplace by breathing it in, skin contact, and eye contact.
United States[edit]
The Occupational Safety and Health Administration (OSHA) has set the legal limit (permissible exposure limit) for gypsum exposure in the workplace as TWA 15 mg/m3 for total exposure and TWA 5 mg/m3 for respiratory exposure over an 8-hour workday. The National Institute for Occupational Safety and Health (NIOSH) has set a recommended exposure limit (REL) of TWA 10 mg/m3 for total exposure and TWA 5 mg/m3 for respiratory exposure over an 8-hour workday.[18]
Uses[edit]
Gypsum works, Valencian Museum of Ethnology.
Gypsum is used in a wide variety of applications:
Gypsum board[19] is primarily used as a finish for walls and ceilings, and is known in construction as drywall, wallboard, sheetrock or plasterboard.
Gypsum blocks are used like concrete blocks in building construction.
Gypsum mortar is an ancient mortar used in building construction.
Plaster ingredients are used in surgical splints, casting moulds and modeling.
Fertilizer and soil conditioner: In the late 18th and early 19th centuries, Nova Scotia gypsum, often referred to as plaster, was a highly sought fertilizer for wheat fields in the United States. It is also used in ameliorating high-sodium soils.[20]
A binder in fast-dry tennis court clay
As alabaster, a material for sculpture, it was used especially in the ancient world before steel was developed, when its relative softness made it much easier to carve.
A wood substitute in the ancient world: For example, when wood became scarce due to deforestation on Bronze Age Crete, gypsum was employed in building construction at locations where wood was previously used.[21]
A tofu (soy bean curd) coagulant, making it ultimately a major source of dietary calcium, especially in Asian cultures which traditionally use few dairy products
Adding hardness to water used for brewing[22]
Used in baking as a dough conditioner, reducing stickiness, and as a baked-goods source of dietary calcium.[23] The primary component of mineral yeast food.[24]
A component of Portland cement used to prevent flash setting of concrete
Soil/water potential monitoring (soil moisture)
A common ingredient in making mead
In the medieval period, scribes and illuminators mixed it with lead carbonate (powdered white lead) to make gesso, which was applied to illuminated letters and gilded with gold in illuminated manuscripts.
In foot creams, shampoos and many other hair products
A medicinal agent in traditional Chinese medicine called shi gao
Impression plasters in dentistry
Used in mushroom cultivation to stop grains from clumping together
Tests have shown that gypsum can be used to remove pollutants such as lead[25] or arsenic[26][27] from contaminated waters.