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About Holmium

Holmium Bohr

In 1878, Marc Delafontain and Jacques-Louis Soret identified spectroscopic absorption bands of an unknown element whose oxide was isolated later that same year by Per Teodor Cleve. All three men are given credit for discovering this new element, which was named holmium after Cleve’s native Stockholm.

Holmium has the greatest magnetic strength of any element, and is used to create extremely strong magnetic fields as a magnetic flux concentrator within high-strength magnets. Holmium is used as a magnet component instead of for fabricating complete magnets because it is extremely rare.

Holmium’s other primary use is as a dopant in garnets, cubic zirconia, and glass. Holmium garnets are used in solid-state lasers that emit at wavelengths that make them safe for use in medical and dental applications, and they are also used in fiber optic communications devices. In glass and cubic zirconia, holmium provides yellow or red coloring and has distinctive absorption peaks that make them useful as calibration standards for optical spectrophotometers. Additionally, the radioactive isotope holmium-166m1 is used to calibrate gamma ray spectrometers.

Holmium is a rare earth element and can be found in any rare earth containing mineral, but as a heavy rare earth element (HREE) it is more common in HREE-enriched minerals such as xenotime and euxenite. Additionally, holmium is present in ion adsorption clays, which are a major source of HREEs due to their relative ease of processing, despite the low percentage quantities of rare earths they contain.


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Elemental Holmium Picture Holmium has the highest magnetic moment (10.6µB) of any naturally occurring element. Because of this, it has been used to create the strongest known magnetic fields by placing it within high-strength magnets as a pole piece or magnetic flux concentrator. This magnetic property is also exploited in holmium-yttrium iron garnet, a synthetic ferrimagnetic material used in microwave and magnetooptical applications. Holmium lases at a human eye-safe 2.08 microns, allowing its use in a variety of medical and dental applications in both yttrium-aluminum-garnet (YAG) and yttrium-lanthanum-fluoride (YLF) solid state lasers. The wavelength High Purity (99.999%) Holmium Oxide (Ho2O3) Powderallows for use in silica fibers designed for shorter wavelengths while still providing the cutting strength of longer wave length equipment. Holmium is available as metal and compounds with purities from 99% to 99.999% (ACS grade to ultra-high purity). Elemental or metallic forms include pellets, rod, wire and granules for evaporation source material purposes. High Purity (99.999%) Holmium (Ho) Sputtering Target Holmium oxides are available in powder and dense pellet form for such uses as optical coating and thin film applications. Oxides tend to be insoluble. Holmium fluoride is another insoluble form for uses in which oxygen is undesirable such as metallurgy, chemical and physical vapor deposition and in some optical coatings. Holmium is also available in soluble forms including chlorides, nitrates and acetates. These compounds can be manufactured as solutions at specified stoichiometries.

Holmium Properties

Holmium (Ho) atomic and molecular weight, atomic number and elemental symbolHolmium is a Block F, Group 3, Period 6 element. Holmium Bohr ModelThe number of electrons in each of Holmium's shells is 2, 8, 18, 29, 8, 2 and its electronic configuration is [Xe] 4f11 6s2. In its elemental form, CAS 7440-60-0, holmium has a silvery white appearance. The holmium atom has a radius of and its Van der Waals radius is unknown. Holmium was first discovered by J.L. Soret in 1878.

Symbol: Ho
Atomic Number: 67
Atomic Weight: 164.93
Element Category: Lanthanide
Group, Period, Block: n/a, 6, f
Color: silvery-white
Other Names: Olmio, Hólmio
Melting Point: 1472°C, 2681.6°F, 1745.15 K
Boiling Point: 2700°C, 4892°F, 2973.15 K
Density: 8.795 g/cm3
Liquid Density @ Melting Point: 8.34 g/cm3
Density @ 20°C: 8.80 g/cm3
Density of Solid: 8795 kg·m3
Specific Heat: 0.0393 Cal/g/ K @ 25 °C
Superconductivity Temperature: N/A
Triple Point: N/A
Critical Point: N/A
Heat of Fusion (kJ·mol-1): 17.2
Heat of Vaporization (kJ·mol-1): 303
Heat of Atomization (kJ·mol-1): 302.63
Thermal Conductivity: 0.162 W/cm/ K @ 298.2 K
Thermal Expansion: (r.t.) (poly) 11.2 µm/(m·K)
Electrical Resistivity: 87.0 nΩ-cm @ 25°C
Tensile Strength: N/A
Molar Heat Capacity: 27.15 J·mol-1·K-1
Young's Modulus: 64.8 GPa
Shear Modulus: 26.3 GPa
Bulk Modulus: 40.2 GPa
Poisson Ratio: 0.231
Mohs Hardness: N/A
Vickers Hardness: 481 MPa
Brinell Hardness: 746 MPa
Speed of Sound: (20 °C) 2760 m·s-1
Pauling Electronegativity: 1.23
Sanderson Electronegativity: N/A
Allred Rochow Electronegativity: 1.1
Mulliken-Jaffe Electronegativity: N/A
Allen Electronegativity: N/A
Pauling Electropositivity: 2.77
Reflectivity (%): N/A
Refractive Index: N/A
Electrons: 67
Protons: 67
Neutrons: 98
Electron Configuration: [Xe] 4f11 6s2
Atomic Radius: 176 pm
Atomic Radius,
non-bonded (Å):
Covalent Radius: 192±7 pm
Covalent Radius (Å): 1.79
Van der Waals Radius: 216 pm
Oxidation States: 3, 2, 1 (basic oxide)
Phase: Solid
Crystal Structure: hexagonal close-packed
Magnetic Ordering: paramagnetic
Electron Affinity (kJ·mol-1) Unknown
1st Ionization Energy: 580.99 kJ·mol-1
2nd Ionization Energy: 1138.54 kJ·mol-1
3rd Ionization Energy: 2203.74 kJ·mol-1
CAS Number: 7440-60-0
EC Number: 231-169-0
MDL Number: MFCD00011049
Beilstein Number: N/A
SMILES Identifier: [Ho]
InChI Identifier: InChI=1S/Ho
PubChem CID: 23988
ChemSpider ID: 22424
Earth - Total: 80 ppb
Mercury - Total: 61 ppb
Venus - Total: 84 ppb
Earth - Seawater (Oceans), ppb by weight: 0.00022
Earth - Seawater (Oceans), ppb by atoms: 0.000008
Earth -  Crust (Crustal Rocks), ppb by weight: 1200
Earth -  Crust (Crustal Rocks), ppb by atoms: 150
Sun - Total, ppb by weight: N/A
Sun - Total, ppb by atoms: N/A
Stream, ppb by weight: 0.01
Stream, ppb by atoms: 0.0001
Meterorite (Carbonaceous), ppb by weight: 60
Meterorite (Carbonaceous), ppb by atoms: 7
Typical Human Body, ppb by weight: N/A
Typical Human Body, ppb by atom: N/A
Universe, ppb by weight: 0.5
Universe, ppb by atom: 0.004
Discovered By: Marc Delafontaine
Discovery Date: 1878
First Isolation: N/A

Health, Safety & Transportation Information for Holmium

Holmium is slightly toxic in its elemental form. Safety data for Holmium and its compounds can vary widely depending on the form. For potential hazard information, toxicity, and road, sea and air transportation limitations, such as DOT Hazard Class, DOT Number, EU Number, NFPA Health rating and RTECS Class, please see the specific material or compound referenced in the Products tab.

Safety Data
Signal Word Danger
Hazard Statements H228
Hazard Codes F
Risk Codes 11
Safety Precautions N/A
RTECS Number N/A
Transport Information N/A
WGK Germany 3
Globally Harmonized System of
Classification and Labelling (GHS)
Review and Print SDS for Holmium Metal


Date Created: 05/15/2015
Date Revised: 05/15/2015


Product Name: Holmium Metal

Product Number: All applicable American Elements product codes, e.g. HO-M-02, HO-M-03, HO-M-04, HO-M-05

CAS #: 7440-60-0

Relevant identified uses of the substance: Scientific research and development

Supplier details:
American Elements
1093 Broxton Ave. Suite 2000
Los Angeles, CA 90024
Tel: +1 310-208-0551
Fax: +1 310-208-0351

Emergency telephone number:
Domestic, North America +1 800-424-9300
International +1 703-527-3887


Classification of the substance or mixture in accordance with 29 CFR 1910 (OSHA HCS)
The substance is not classified according
to the Globally Harmonized System (GHS).
Hazards not otherwise classified
No information known.
Label elements
GHS label elements
Not applicable
Hazard pictograms
Not applicable
Signal word
Not applicable
Hazard statements
Not applicable
WHMIS classification
Not controlled
Classification system
HMIS ratings (scale 0-4)
(Hazardous Materials Identification System)

Health (acute effects) = 0
Flammability = 0
Physical Hazard = 0
Other hazards
Results of PBT and vPvB assessment
Not applicable.
Not applicable.


Chemical characterization: Substances
CAS# Description:
7440-60-0 Holmium
Identification number(s):
EC number:


Description of first aid measures
After inhalation
Supply fresh air. If required, provide artificial respiration. Keep patient warm.
Seek immediate medical advice.
After skin contact
Immediately wash with water and soap and rinse thoroughly.
Seek immediate medical advice.
After eye contact
Rinse opened eye for several minutes under running water. Then consult a doctor.
After swallowing
Seek medical treatment.
Information for doctor
Most important symptoms and effects, both acute and delayed
No further relevant information available.
Indication of any immediate medical attention and special treatment needed
No further relevant information available.


Extinguishing media
Suitable extinguishing agents
Special powder for metal fires. Do not use water.
For safety reasons unsuitable extinguishing agents
Special hazards arising from the substance or mixture
If this product is involved in a fire, the following can be released:
Metal oxide fume
Advice for firefighters
Protective equipment:
No special measures required.


Personal precautions, protective equipment and emergency procedures
Not required.
Environmental precautions:
Do not allow material to be released to the environment without proper governmental permits.
Methods and material for containment and cleaning up:
Pick up mechanically.
Prevention of secondary hazards:
No special measures required.
Reference to other sections
See Section 7 for information on safe handling
See Section 8 for information on personal protection equipment.
See Section 13 for disposal information.


Precautions for safe handling
Keep container tightly sealed.
Store in cool, dry place in tightly closed containers.
Information about protection against explosions and fires:
No special measures required.
Conditions for safe storage, including any incompatibilities
Requirements to be met by storerooms and receptacles:
No special requirements.
Information about storage in one common storage facility:
Not required.
Further information about storage conditions:
Keep container tightly sealed.
Store in cool, dry conditions in well sealed containers.
Specific end use(s)
No further relevant information available.


Additional information about design of technical systems:
No further data; see section 7.
Control parameters
Components with limit values that require monitoring at the workplace:
Not required.
Additional information:
No data
Exposure controls
Personal protective equipment
General protective and hygienic measures
The usual precautionary measures for handling chemicals should be followed.
Maintain an ergonomically appropriate working environment.
Breathing equipment:
Not required.
Protection of hands:
Not required.
Penetration time of glove material (in minutes)
Not determined
Eye protection:
Safety glasses
Body protection:
Protective work clothing.


Information on basic physical and chemical properties
General Information
Form: Solid in various forms
Color: Not determined
Odor: Not determined
Odor threshold: Not determined.
pH-value: Not applicable.
Change in condition
Melting point/Melting range: 1474 °C (2685 °F)
Boiling point/Boiling range: 2295 °C (4163 °F)
Sublimation temperature / start: Not determined
Flammability (solid, gaseous)
Not determined.
Ignition temperature: Not determined
Decomposition temperature: Not determined
Auto igniting: Not determined.
Danger of explosion: Product does not present an explosion hazard.
Explosion limits:
Lower: Not determined
Upper: Not determined
Vapor pressure at 20 °C (68 °F): 0 hPa
Density at 20 °C (68 °F): 8.795 g/cm³ (73.394 lbs/gal)
Relative density
Not determined.
Vapor density
Not applicable.
Evaporation rate
Not applicable.
Solubility in / Miscibility with Water: Not determined
Partition coefficient (n-octanol/water): Not determined.
dynamic: Not applicable.
kinematic: Not applicable.
Other information
No further relevant information available.


No information known.
Chemical stability
Stable under recommended storage conditions.
Thermal decomposition / conditions to be avoided:
Decomposition will not occur if used and stored according to specifications.
Possibility of hazardous reactions
No dangerous reactions known
Conditions to avoid
No further relevant information available.
Incompatible materials:
No information known.
Hazardous decomposition products:
Metal oxide fume


Information on toxicological effects
Acute toxicity:
No effects known.
LD/LC50 values that are relevant for classification:
No data
Skin irritation or corrosion:
Powder: irritant effect
Eye irritation or corrosion:
Powder: irritant effect
No sensitizing effects known.
Germ cell mutagenicity:
No effects known.
No classification data on carcinogenic properties of this material is available from the EPA, IARC, NTP, OSHA or ACGIH.
Reproductive toxicity:
No effects known.
Specific target organ system toxicity - repeated exposure:
No effects known
Specific target organ system toxicity - single exposure:
No effects known.
Aspiration hazard:
No effects known.
Subacute to chronic toxicity:
Lanthanons can cause delayed blood clotting leading to hemorrhages.
Exposure may also lead to sensitivity to heat, itching, increased awareness of odor and taste,
and liver damage.
Subacute to chronic toxicity:
No effects known.
Additional toxicological information:
To the best of our knowledge the acute and chronic toxicity of this substance is not fully known.


Aquatic toxicity:
No further relevant information available.
Persistence and degradability
No further relevant information available.
Bioaccumulative potential
No further relevant information available.
Mobility in soil
No further relevant information available.
Additional ecological information:
General notes:
Do not allow material to be released to the environment without proper governmental permits.
Do not allow undiluted product or large quantities to reach ground water, water course or sewage system.
Avoid transfer into the environment.
Results of PBT and vPvB assessment
Not applicable.
Not applicable.
Other adverse effects
No further relevant information available.


Waste treatment methods
Consult state, local or national regulations to ensure proper disposal.
Uncleaned packagings:
Disposal must be made according to official regulations.


Not a hazardous material for transportation.
UN proper shipping name
Transport hazard class(es)
Packing group
Environmental hazards:
Not applicable.
Special precautions for user
Not applicable.
Transport in bulk according to Annex II of MARPOL73/78 and the IBC Code
Not applicable.
Transport/Additional information:
Not dangerous according to
the above specifications.
Marine Pollutant (DOT):


Safety, health and environmental regulations/legislation specific for the substance or mixture
GHS label elements
Not applicable
Hazard pictograms
Not applicable
Signal word
Not applicable
Hazard statements
Not applicable
National regulations
All components of this product are listed in the U.S. Environmental Protection Agency Toxic Substances Control Act Chemical substance Inventory.
All components of this product are listed on the Canadian Non-Domestic Substances List (NDSL).
SARA Section 313 (specific toxic chemical listings)
Substance is not listed.
California Proposition 65
Prop 65 - Chemicals known to cause cancer
Substance is not listed.
Prop 65 - Developmental toxicity
Substance is not listed.
Prop 65 - Developmental toxicity, female
Substance is not listed.
Prop 65 - Developmental toxicity, male
Substance is not listed.
Information about limitation of use:
For use only by technically qualified individuals.
Other regulations, limitations and prohibitive regulations
Substance of Very High Concern (SVHC) according to the REACH Regulations (EC) No. 1907/2006.
Substance is not listed.
The conditions of restrictions according to Article 67 and Annex XVII of the Regulation (EC) No 1907/2006 (REACH) for the manufacturing, placing on the market and use must be observed.
Substance is not listed.
Annex XIV of the REACH Regulations (requiring Authorisation for use)
Substance is not listed.
Chemical safety assessment:
A Chemical Safety Assessment has not been carried out.


Safety Data Sheet according to Regulation (EC) No. 1907/2006 (REACH). The above information is believed to be correct but does not purport to be all inclusive and shall be used only as a guide. The information in this document is based on the present state of our knowledge and is applicable to the product with regard to appropriate safety precautions. It does not represent any guarantee of the properties of the product. American Elements shall not be held liable for any damage resulting from handling or from contact with the above product. See reverse side of invoice or packing slip for additional terms and conditions of sale. COPYRIGHT 1997-2016 AMERICAN ELEMENTS. LICENSED GRANTED TO MAKE UNLIMITED PAPER COPIES FOR INTERNAL USE ONLY.

Holmium Isotopes

Holmium has one stable isotope: 165Ho.

Nuclide Isotopic Mass Half-Life Mode of Decay Nuclear Spin Magnetic Moment Binding Energy (MeV) Natural Abundance
(% by atom)
140Ho 139.96854(54)# 6(3) ms Unknown 8+# N/A 1093.11 -
141Ho 140.96310(54)# 4.1(3) ms Unknown (7/2-) N/A 1101.18 -
142Ho 141.95977(54)# 400(100) ms ß+ to 142Dy; p to 141Dy (6 to 9) N/A 1118.58 -
143Ho 142.95461(43)# 300# ms [>200 ns] ß+ to 143Dy 11/2-# N/A 1126.66 -
144Ho 143.95148(32)# 0.7(1) s ß+ to 144Dy; ß+ + p to 143Tb N/A N/A 1134.74 -
145Ho 144.94720(32)# 2.4(1) s ß+ to 145Dy (11/2-) N/A 1152.13 -
146Ho 145.94464(21)# 3.6(3) s ß+ to 146Dy; ß+ + p to 145Tb (10+) N/A 1160.21 -
147Ho 146.94006(3) 5.8(4) s ß+ to 147Dy; ß+ + p to 146Tb (11/2-) N/A 1168.29 -
148Ho 147.93772(14) 2.2(11) s ß+ to 148Dy (1+) N/A 1185.68 -
149Ho 148.933775(20) 21.1(2) s ß+ to 149Dy (11/2-) N/A 1193.76 -
150Ho 149.933496(15) 76.8(18) s ß+ to 150Dy 2- N/A 1201.84 -
151Ho 150.931688(13) 35.2(1) s ß+ to 151Dy; a to 147Tb 11/2(-) N/A 1209.92 -
152Ho 151.931714(15) 161.8(3) s ß+ to 152Dy; a to 148Tb 2- N/A 1218 -
153Ho 152.930199(6) 2.01(3) min ß+ to 153Dy; a to 149Tb 11/2- N/A 1226.08 -
154Ho 153.930602(9) 11.76(19) min ß+ to 154Dy; a to 150Tb 2- N/A 1234.16 -
155Ho 154.929103(19) 48(1) min ß+ to 155Dy 5/2+ N/A 1251.55 -
156Ho 155.92984(5) 56(1) min ß+ to 156Dy 4- N/A 1259.63 -
157Ho 156.928256(26) 12.6(2) min ß+ to 157Dy 7/2- N/A 1267.71 -
158Ho 157.928941(29) 11.3(4) min ß+ to 158Dy; a to 154Tb 5+ N/A 1275.79 -
159Ho 158.927712(4) 33.05(11) min ß+ to 159Dy 7/2- N/A 1283.87 -
160Ho 159.928729(16) 25.6(3) min ß+ to 160Dy 5+ N/A 1291.95 -
161Ho 160.927855(3) 2.48(5) h EC to 161Dy 7/2- 4.25 1300.02 -
162Ho 161.929096(4) 15.0(10) min EC to 161Dy 1+ N/A 1308.1 -
163Ho 162.9287339(27) 4570(25) y EC to 161Dy 7/2- 4.23 1316.18 -
164Ho 163.9302335(30) 29(1) min EC to 161Dy; ß- to 164Er 1+ N/A 1314.94 -
165Ho 164.9303221(27) Observationally Stable - 7/2- 4.173 1323.02 100
166Ho 165.9322842(27) 26.83(2) h ß- to 166Er 0- N/A 1331.1 -
167Ho 166.933133(6) 3.003(18) h ß- to 167Er 7/2- N/A 1339.18 -
168Ho 167.93552(3) 2.99(7) min ß- to 168Er 3+ N/A 1347.26 -
169Ho 168.936872(22) 4.72(10) min ß- to 169Er 7/2- N/A 1355.34 -
170Ho 169.93962(5) 2.76(5) min ß- to 170Er 6+# N/A 1363.42 -
171Ho 170.94147(64) 53(2) s ß- to 171Er 7/2-# N/A 1362.18 -
172Ho 171.94482(43)# 25(3) s ß- to 172Er N/A N/A 1370.26 -
173Ho 172.94729(43)# 10# s ß- to 173Er 7/2-# N/A 1378.34 -
174Ho 173.95115(54)# 8# s Unknown N/A N/A 1377.1 -
175Ho 174.95405(64)# 5# s Unknown 7/2-# N/A 1385.18 -