The Flickr Sovietsky Image Generatr

Fluorite-manganoan calcite from Russia.

Greenish = fluorite (CaF2, calcium fluoride)
Light-colored = manganoan calcite (Mn-bearing CaCO3, calcium carbonate)

A mineral is a naturally-occurring, solid, inorganic, crystalline substance having a fairly definite chemical composition and having fairly definite physical properties. At its simplest, a mineral is a naturally-occurring solid chemical. Currently, there are about 6100 named and described minerals - about 200 of them are common and about 20 of them are very common. Mineral classification is based on anion chemistry. Major categories of minerals are: elements, sulfides, oxides, halides, carbonates, sulfates, phosphates, and silicates.

The halides are the "salt minerals", and have one or more of the following anions: Cl-, F-, I-, Br-.

Fluorite is a calcium fluoride mineral (CaF2). The most diagnostic physical property of fluorite is its hardness (H≡4). Fluorite typically forms cubic crystals and, when broken, displays four cleavage planes (also quite diagnostic). When broken under controlled conditions, the broken pieces of fluorite form double pyramids. Fluorite is a good example of a mineral that can be any color. Common fluorite colors include clear, purple, blue, green, yellow, orange, and brown. The stereotypical color for fluorite is purple. Purple is the color fluorite "should be". A mineral collector doesn't have fluorite unless it's a purple fluorite (!).

Fluorite occurs in association with some active volcanoes. HF emitted from volcanoes can react with Ca-bearing rocks to form fluorite crystals. Many hydrothermal veins contain fluorite. Much fluorite occurs in the vicinity of southern Illinois (Mississippi Valley-type deposits).

The fluorite-calcite specimen seen here comes from the famous Dalnegorsk Skarn Deposit in Russia. The deposit consists of mineral-filled solution cavities in Triassic limestones that have been intruded by Late Cretaceous granodiorites. The skarn zone itself has been intruded by 64 Ma granite.

Geologic unit: Dalnegorsk Skarn Deposit, Late Cretaceous, 70-90 Ma

Locality: 2nd Sovietsky Mine, southern Sikhote-Alin Mountains, Maritime Region ("Primorskiy Kray"), far-eastern Russia
------------------------
Photo gallery of fluorite:
www.mindat.org/gallery.php?min=1576

Quartz crystals from the Cretaceous of Russia.

A mineral is a naturally-occurring, solid, inorganic, crystalline substance having a fairly definite chemical composition and having fairly definite physical properties. At its simplest, a mineral is a naturally-occurring solid chemical. Currently, there are over 6100 named and described minerals - about 200 of them are common and about 20 of them are very common. Mineral classification is based on anion chemistry. Major categories of minerals are: elements, sulfides, oxides, halides, carbonates, sulfates, phosphates, and silicates.

The silicates are the most abundant and chemically complex group of minerals. All silicates have silica as the basis for their chemistry. "Silica" refers to SiO2 chemistry. The fundamental molecular unit of silica is one small silicon atom surrounded by four large oxygen atoms in the shape of a triangular pyramid - this is the silica tetrahedron - SiO4. Each oxygen atom is shared by two silicon atoms, so only half of the four oxygens "belong" to each silicon. The resulting formula for silica is thus SiO2, not SiO4.

The simplest & most abundant silicate mineral in the Earth's crust is quartz (SiO2). All other silicates have silica + impurities. Many silicates have a significant percentage of aluminum (the aluminosilicates).

Quartz (silicon dioxide/silica - SiO2) is the most common mineral in the Earth's crust. It is composed of the two most abundant elements in the crust - oxygen and silicon. It has a glassy, nonmetallic luster, is commonly clearish to whitish to grayish in color, has a white streak, is quite hard (H≡7), forms hexagonal crystals (even though it's in the trigonal crystal system), has no cleavage, and has conchoidal fracture. Quartz can be any color: clear, white, gray, black, brown, pink, red, purple, blue, green, orange, etc.

The quartz crystals seen here come from the famous Dalnegorsk Skarn Deposit in Russia. The deposit consists of mineral-filled solution cavities in Triassic limestones that have been intruded by Late Cretaceous granodiorites. The skarn zone itself has been intruded by 64 Ma granite.

The reddish color of the quartz is from inclusions of hematite, Fe2O3 - iron oxide.

Geologic unit: Dalnegorsk Skarn Deposit, Late Cretaceous, 70-90 Ma

Locality: 2nd Sovietsky Mine, southern Sikhote-Alin Mountains, Maritime Region ("Primorskiy Kray"), far-eastern Russia

Quartz crystals from the Cretaceous of Russia.

A mineral is a naturally-occurring, solid, inorganic, crystalline substance having a fairly definite chemical composition and having fairly definite physical properties. At its simplest, a mineral is a naturally-occurring solid chemical. Currently, there are over 6100 named and described minerals - about 200 of them are common and about 20 of them are very common. Mineral classification is based on anion chemistry. Major categories of minerals are: elements, sulfides, oxides, halides, carbonates, sulfates, phosphates, and silicates.

The silicates are the most abundant and chemically complex group of minerals. All silicates have silica as the basis for their chemistry. "Silica" refers to SiO2 chemistry. The fundamental molecular unit of silica is one small silicon atom surrounded by four large oxygen atoms in the shape of a triangular pyramid - this is the silica tetrahedron - SiO4. Each oxygen atom is shared by two silicon atoms, so only half of the four oxygens "belong" to each silicon. The resulting formula for silica is thus SiO2, not SiO4.

The simplest & most abundant silicate mineral in the Earth's crust is quartz (SiO2). All other silicates have silica + impurities. Many silicates have a significant percentage of aluminum (the aluminosilicates).

Quartz (silicon dioxide/silica - SiO2) is the most common mineral in the Earth's crust. It is composed of the two most abundant elements in the crust - oxygen and silicon. It has a glassy, nonmetallic luster, is commonly clearish to whitish to grayish in color, has a white streak, is quite hard (H≡7), forms hexagonal crystals (even though it's in the trigonal crystal system), has no cleavage, and has conchoidal fracture. Quartz can be any color: clear, white, gray, black, brown, pink, red, purple, blue, green, orange, etc.

The quartz crystals seen here come from the famous Dalnegorsk Skarn Deposit in Russia. The deposit consists of mineral-filled solution cavities in Triassic limestones that have been intruded by Late Cretaceous granodiorites. The skarn zone itself has been intruded by 64 Ma granite.

The reddish color of the quartz is from inclusions of hematite, Fe2O3 - iron oxide.

Geologic unit: Dalnegorsk Skarn Deposit, Late Cretaceous, 70-90 Ma

Locality: 2nd Sovietsky Mine, southern Sikhote-Alin Mountains, Maritime Region ("Primorskiy Kray"), far-eastern Russia

Quartz crystal from the Cretaceous of Russia.

A mineral is a naturally-occurring, solid, inorganic, crystalline substance having a fairly definite chemical composition and having fairly definite physical properties. At its simplest, a mineral is a naturally-occurring solid chemical. Currently, there are over 6100 named and described minerals - about 200 of them are common and about 20 of them are very common. Mineral classification is based on anion chemistry. Major categories of minerals are: elements, sulfides, oxides, halides, carbonates, sulfates, phosphates, and silicates.

The silicates are the most abundant and chemically complex group of minerals. All silicates have silica as the basis for their chemistry. "Silica" refers to SiO2 chemistry. The fundamental molecular unit of silica is one small silicon atom surrounded by four large oxygen atoms in the shape of a triangular pyramid - this is the silica tetrahedron - SiO4. Each oxygen atom is shared by two silicon atoms, so only half of the four oxygens "belong" to each silicon. The resulting formula for silica is thus SiO2, not SiO4.

The simplest & most abundant silicate mineral in the Earth's crust is quartz (SiO2). All other silicates have silica + impurities. Many silicates have a significant percentage of aluminum (the aluminosilicates).

Quartz (silicon dioxide/silica - SiO2) is the most common mineral in the Earth's crust. It is composed of the two most abundant elements in the crust - oxygen and silicon. It has a glassy, nonmetallic luster, is commonly clearish to whitish to grayish in color, has a white streak, is quite hard (H≡7), forms hexagonal crystals (even though it's in the trigonal crystal system), has no cleavage, and has conchoidal fracture. Quartz can be any color: clear, white, gray, black, brown, pink, red, purple, blue, green, orange, etc.

The quartz crystal seen here comes from the famous Dalnegorsk Skarn Deposit in Russia. The deposit consists of mineral-filled solution cavities in Triassic limestones that have been intruded by Late Cretaceous granodiorites. The skarn zone itself has been intruded by 64 Ma granite.

The olive green color of this quartz is from inclusions of hedenbergite pyroxene, CaFeSi2O6 - calcium iron silicate.

Geologic unit: Dalnegorsk Skarn Deposit, Late Cretaceous, 70-90 Ma

Locality: 2nd Sovietsky Mine, southern Sikhote-Alin Mountains, Maritime Region ("Primorskiy Kray"), far-eastern Russia

Quartz crystal from the Cretaceous of Russia.

A mineral is a naturally-occurring, solid, inorganic, crystalline substance having a fairly definite chemical composition and having fairly definite physical properties. At its simplest, a mineral is a naturally-occurring solid chemical. Currently, there are over 6100 named and described minerals - about 200 of them are common and about 20 of them are very common. Mineral classification is based on anion chemistry. Major categories of minerals are: elements, sulfides, oxides, halides, carbonates, sulfates, phosphates, and silicates.

The silicates are the most abundant and chemically complex group of minerals. All silicates have silica as the basis for their chemistry. "Silica" refers to SiO2 chemistry. The fundamental molecular unit of silica is one small silicon atom surrounded by four large oxygen atoms in the shape of a triangular pyramid - this is the silica tetrahedron - SiO4. Each oxygen atom is shared by two silicon atoms, so only half of the four oxygens "belong" to each silicon. The resulting formula for silica is thus SiO2, not SiO4.

The simplest & most abundant silicate mineral in the Earth's crust is quartz (SiO2). All other silicates have silica + impurities. Many silicates have a significant percentage of aluminum (the aluminosilicates).

Quartz (silicon dioxide/silica - SiO2) is the most common mineral in the Earth's crust. It is composed of the two most abundant elements in the crust - oxygen and silicon. It has a glassy, nonmetallic luster, is commonly clearish to whitish to grayish in color, has a white streak, is quite hard (H≡7), forms hexagonal crystals (even though it's in the trigonal crystal system), has no cleavage, and has conchoidal fracture. Quartz can be any color: clear, white, gray, black, brown, pink, red, purple, blue, green, orange, etc.

The quartz crystal seen here comes from the famous Dalnegorsk Skarn Deposit in Russia. The deposit consists of mineral-filled solution cavities in Triassic limestones that have been intruded by Late Cretaceous granodiorites. The skarn zone itself has been intruded by 64 Ma granite.

The olive green color of this quartz is from inclusions of hedenbergite pyroxene, CaFeSi2O6 - calcium iron silicate.

Geologic unit: Dalnegorsk Skarn Deposit, Late Cretaceous, 70-90 Ma

Locality: 2nd Sovietsky Mine, southern Sikhote-Alin Mountains, Maritime Region ("Primorskiy Kray"), far-eastern Russia

Siderite from the Cretaceous of Russia. (Wayne State University collection, Detroit, Michigan, USA)

A mineral is a naturally-occurring, solid, inorganic, crystalline substance having a fairly definite chemical composition and having fairly definite physical properties. At its simplest, a mineral is a naturally-occurring solid chemical. Currently, there are over 6100 named and described minerals - about 200 of them are common and about 20 of them are very common. Mineral classification is based on anion chemistry. Major categories of minerals are: elements, sulfides, oxides, halides, carbonates, sulfates, phosphates, and silicates.

The carbonate minerals all contain one or more carbonate (CO3-2) anions.

Siderite is an iron carbonate mineral - FeCO3. It is moderately common in hydrothermal veins, some concretions, and in some Precambrian-aged banded iron formations (BIFs). Siderite is usually light brown to dark brown to reddish brown in color. It tends to form distinctive rhombohedral crystals with curved crystal faces (dolomite crystals do this as well). Siderite also has three cleavage planes not at right angles (rhombohedral cleavage). Due to its iron content, siderite is moderately dense.

This siderite specimen comes from the famous Dalnegorsk Skarn Deposit, a polymetallic sulfide ore body in far-eastern Russia. The deposit consists of mineral-filled solution cavities in Triassic limestones that have been intruded by Late Cretaceous granodiorites. The skarn zone itself has been intruded by 64 Ma granite.

Geologic unit: Dalnegorsk Skarn Deposit, Late Cretaceous, 70-90 Ma

Locality: 2nd Sovietsky Mine, southern Sikhote-Alin Mountains, Maritime Region ("Primorskiy Kray"), far-eastern Russia
--------------
Photo gallery of siderite:
www.mindat.org/gallery.php?min=3647

Siderite from the Cretaceous of Russia. (Wayne State University collection, Detroit, Michigan, USA)

A mineral is a naturally-occurring, solid, inorganic, crystalline substance having a fairly definite chemical composition and having fairly definite physical properties. At its simplest, a mineral is a naturally-occurring solid chemical. Currently, there are over 6100 named and described minerals - about 200 of them are common and about 20 of them are very common. Mineral classification is based on anion chemistry. Major categories of minerals are: elements, sulfides, oxides, halides, carbonates, sulfates, phosphates, and silicates.

The carbonate minerals all contain one or more carbonate (CO3-2) anions.

Siderite is an iron carbonate mineral - FeCO3. It is moderately common in hydrothermal veins, some concretions, and in some Precambrian-aged banded iron formations (BIFs). Siderite is usually light brown to dark brown to reddish brown in color. It tends to form distinctive rhombohedral crystals with curved crystal faces (dolomite crystals do this as well). Siderite also has three cleavage planes not at right angles (rhombohedral cleavage). Due to its iron content, siderite is moderately dense.

This siderite specimen comes from the famous Dalnegorsk Skarn Deposit, a polymetallic sulfide ore body in far-eastern Russia. The deposit consists of mineral-filled solution cavities in Triassic limestones that have been intruded by Late Cretaceous granodiorites. The skarn zone itself has been intruded by 64 Ma granite.

Geologic unit: Dalnegorsk Skarn Deposit, Late Cretaceous, 70-90 Ma

Locality: 2nd Sovietsky Mine, southern Sikhote-Alin Mountains, Maritime Region ("Primorskiy Kray"), far-eastern Russia
--------------
Photo gallery of siderite:
www.mindat.org/gallery.php?min=3647

Chalcopyrite-galena from the Cretaceous of Russia.

A mineral is a naturally-occurring, solid, inorganic, crystalline substance having a fairly definite chemical composition and having fairly definite physical properties. At its simplest, a mineral is a naturally-occurring solid chemical. Currently, there are over 6100 named and described minerals - about 200 of them are common and about 20 of them are very common. Mineral classification is based on anion chemistry. Major categories of minerals are: elements, sulfides, oxides, halides, carbonates, sulfates, phosphates, and silicates.

The sulfide minerals contain one or more sulfide anions (S-2). The sulfides are usually considered together with the arsenide minerals, the sulfarsenide minerals, and the telluride minerals. Many sulfides are economically significant, as they occur commonly in ores. The metals that combine with S-2 are mainly Fe, Cu, Ni, Ag, etc. Most sulfides have a metallic luster, are moderately soft, and are noticeably heavy for their size. These minerals will not form in the presence of free oxygen. Under an oxygen-rich atmosphere, sulfide minerals tend to chemically weather to various oxide and hydroxide minerals.

Chalcopyrite is a copper iron sulfide mineral (CuFeS2). Many pyrite-like minerals exist, such as pyrite, marcasite, arsenopyrite, pyrrhotite, and chalcopyrite. Chalcopyrite has a metallic luster, a deep yellowish-brassy color, a dark gray streak, a hardness of about 3.5 to 4, and no cleavage. Many specimens have a multicolored iridescent tarnish, which can be artificially produced by exposure to certain chemicals - often acid. Chalcopyrite is an important copper ore mineral.

Galena is a lead sulfide mineral (PbS). It has a metallic luster, silvery-gray color, cubic crystals, cubic cleavage, is moderately soft, and has a very high specific gravity (it's very heavy for its size).

Galena is the most important lead ore mineral. It's principally found in hydrothermal vein systems and in Mississippi Valley-type deposits. Silver (Ag) can fall into the lead position as an impurity, sometimes in relatively high proportions. This results in argentiferous galena, (Pb,Ag)S.

Historically, lead from galena has been used as a gasoline additive, a paint ingredient, and for making bullets. Lead is also used to make various metal products, batteries, and radiation shielding.

This chalcopyrite-galena specimen comes from the famous Dalnegorsk Skarn Deposit, a polymetallic sulfide ore body in far-eastern Russia. The deposit consists of mineral-filled solution cavities in Triassic limestones that have been intruded by Late Cretaceous granodiorites. The skarn zone itself has been intruded by 64 Ma granite.
--------------------------------
Exhibit info.:

A Classic Mineral Locality
The Second Soviet Mine
Dalnegorsk, Russia

Beautiful mineral specimens occur in mines near Dalnegorsk in eastern Russia. In a complex series of geological events, skarn bodies have replaced the host limestones, depositing sulfide ores and other minerals in faults, veins, and solution cavities.

CALCITE
CHALCOPYRITE
FLUORITE
GALENA
HEDENBERGITE
HEMATITE
ILVAITE
QUARTZ
SPHALERITE
--------------------------------
Geologic unit: Dalnegorsk Skarn Deposit, Late Cretaceous, 70-90 Ma

Locality: 2nd Sovietsky Mine, southern Sikhote-Alin Mountains, Maritime Region ("Primorskiy Kray"), far-eastern Russia
--------------------------------
Photo gallery of chalcopyrite:
www.mindat.org/gallery.php?min=955
--------------------------------
Photo gallery of galena:
www.mindat.org/gallery.php?min=1641

Chalcopyrite-galena from the Cretaceous of Russia.

A mineral is a naturally-occurring, solid, inorganic, crystalline substance having a fairly definite chemical composition and having fairly definite physical properties. At its simplest, a mineral is a naturally-occurring solid chemical. Currently, there are over 6100 named and described minerals - about 200 of them are common and about 20 of them are very common. Mineral classification is based on anion chemistry. Major categories of minerals are: elements, sulfides, oxides, halides, carbonates, sulfates, phosphates, and silicates.

The sulfide minerals contain one or more sulfide anions (S-2). The sulfides are usually considered together with the arsenide minerals, the sulfarsenide minerals, and the telluride minerals. Many sulfides are economically significant, as they occur commonly in ores. The metals that combine with S-2 are mainly Fe, Cu, Ni, Ag, etc. Most sulfides have a metallic luster, are moderately soft, and are noticeably heavy for their size. These minerals will not form in the presence of free oxygen. Under an oxygen-rich atmosphere, sulfide minerals tend to chemically weather to various oxide and hydroxide minerals.

Chalcopyrite is a copper iron sulfide mineral (CuFeS2). Many pyrite-like minerals exist, such as pyrite, marcasite, arsenopyrite, pyrrhotite, and chalcopyrite. Chalcopyrite has a metallic luster, a deep yellowish-brassy color, a dark gray streak, a hardness of about 3.5 to 4, and no cleavage. Many specimens have a multicolored iridescent tarnish, which can be artificially produced by exposure to certain chemicals - often acid. Chalcopyrite is an important copper ore mineral.

Galena is a lead sulfide mineral (PbS). It has a metallic luster, silvery-gray color, cubic crystals, cubic cleavage, is moderately soft, and has a very high specific gravity (it's very heavy for its size).

Galena is the most important lead ore mineral. It's principally found in hydrothermal vein systems and in Mississippi Valley-type deposits. Silver (Ag) can fall into the lead position as an impurity, sometimes in relatively high proportions. This results in argentiferous galena, (Pb,Ag)S.

Historically, lead from galena has been used as a gasoline additive, a paint ingredient, and for making bullets. Lead is also used to make various metal products, batteries, and radiation shielding.

This chalcopyrite-galena specimen comes from the famous Dalnegorsk Skarn Deposit, a polymetallic sulfide ore body in far-eastern Russia. The deposit consists of mineral-filled solution cavities in Triassic limestones that have been intruded by Late Cretaceous granodiorites. The skarn zone itself has been intruded by 64 Ma granite.
--------------------------------
Exhibit info.:

A Classic Mineral Locality
The Second Soviet Mine
Dalnegorsk, Russia

Beautiful mineral specimens occur in mines near Dalnegorsk in eastern Russia. In a complex series of geological events, skarn bodies have replaced the host limestones, depositing sulfide ores and other minerals in faults, veins, and solution cavities.

CALCITE
CHALCOPYRITE
FLUORITE
GALENA
HEDENBERGITE
HEMATITE
ILVAITE
QUARTZ
SPHALERITE
--------------------------------
Geologic unit: Dalnegorsk Skarn Deposit, Late Cretaceous, 70-90 Ma

Locality: 2nd Sovietsky Mine, southern Sikhote-Alin Mountains, Maritime Region ("Primorskiy Kray"), far-eastern Russia
--------------------------------
Photo gallery of chalcopyrite:
www.mindat.org/gallery.php?min=955
--------------------------------
Photo gallery of galena:
www.mindat.org/gallery.php?min=1641

Sovietsky Legendary Hotel i aftenbelysning

Calcite from Russia.

A mineral is a naturally-occurring, solid, inorganic, crystalline substance having a fairly definite chemical composition and having fairly definite physical properties. At its simplest, a mineral is a naturally-occurring solid chemical. Currently, there are over 6100 named and described minerals - about 200 of them are common and about 20 of them are very common. Mineral classification is based on anion chemistry. Major categories of minerals are: elements, sulfides, oxides, halides, carbonates, sulfates, phosphates, and silicates.

The carbonate minerals all contain one or more carbonate (CO3-2) anions.

Calcite is a common mineral. It is calcium carbonate (CaCO3). It has a nonmetallic luster, commonly clearish to whitish to yellowish to grayish in color, is moderately soft (H≡3), moderately light-weight, has hexagonal crystals, and rhombohedral cleavage (three cleavage planes at 75º & 105º angles - cleavage pieces look like lopsided boxes). The easiest way to identify calcite is to drop acid on it - it easily bubbles (effervesces) in acid. The bubbles are carbon dioxide gas. If the acid is dilute hydrochloric acid, the chemical reaction is:

2HCl(aq) + CaCO3(s) -->> CO2(g)↑ + H2O(l) + CaCl2(aq)

The most important & voluminous calcitic rocks in the world are limestone (sedimentary), marble (metamorphic), carbonatite (igneous), and travertine (speleothem, or "cave formations", and many hotspring deposits). Quite a few hydrothermal veins in the world are calcitic or have calcite as a principal component.

The remarkable large calcite shown above has an odd crystal form - the label described it as a prism and pinacoid. It comes from a polymetallic sulfide ore body at the famous Dalnegorsk skarn deposit in far-eastern Russia.

Locality: 2nd Sovietsky Mine, Dalnegorsk, far-eastern Russia
---------------------
Photo gallery of calcite:
www.mindat.org/gallery.php?min=859

Calcite from Russia.

A mineral is a naturally-occurring, solid, inorganic, crystalline substance having a fairly definite chemical composition and having fairly definite physical properties. At its simplest, a mineral is a naturally-occurring solid chemical. Currently, there are over 6100 named and described minerals - about 200 of them are common and about 20 of them are very common. Mineral classification is based on anion chemistry. Major categories of minerals are: elements, sulfides, oxides, halides, carbonates, sulfates, phosphates, and silicates.

The carbonate minerals all contain one or more carbonate (CO3-2) anions.

Calcite is a common mineral. It is calcium carbonate (CaCO3). It has a nonmetallic luster, commonly clearish to whitish to yellowish to grayish in color, is moderately soft (H≡3), moderately light-weight, has hexagonal crystals, and rhombohedral cleavage (three cleavage planes at 75º & 105º angles - cleavage pieces look like lopsided boxes). The easiest way to identify calcite is to drop acid on it - it easily bubbles (effervesces) in acid. The bubbles are carbon dioxide gas. If the acid is dilute hydrochloric acid, the chemical reaction is:

2HCl(aq) + CaCO3(s) -->> CO2(g)↑ + H2O(l) + CaCl2(aq)

The most important & voluminous calcitic rocks in the world are limestone (sedimentary), marble (metamorphic), carbonatite (igneous), and travertine (speleothem, or "cave formations", and many hotspring deposits). Quite a few hydrothermal veins in the world are calcitic or have calcite as a principal component.

The remarkable large calcite shown above has an odd crystal form - the label described it as a prism and pinacoid. It comes from a polymetallic sulfide ore body at the famous Dalnegorsk skarn deposit in far-eastern Russia.

Locality: 2nd Sovietsky Mine, Dalnegorsk, far-eastern Russia
---------------------
Photo gallery of calcite:
www.mindat.org/gallery.php?min=859