Mercurous oxide，black

The IUPAC name of Mercurous oxide (CAS NO.15829-53-5): mercuriooxymercury
Synonyms: Mercurous oxide (Hg2O) , Mercury oxide , Mercury oxide (Hg2O) , Mercury oxide black , Mercury(I) oxide , Quecksilberoxid, Quecksilberoxid [German]
CAS: 15829-53-5 
EINECS: 239-934-0 
Molecular Formula: Hg₂O
Formula Weight: 417.1794 g/mol
Molecular Structure:

General Description: Black or brownish-black powder. Not a true compound but rather an intimate mixture of metallic mercury and mercuric oxide. Insoluble in water and denser than water (density 9.8 g / cm3). Hence sinks in water.
Air & Water: Reactions Insoluble in water. 

The toxicity information of Mercurous oxide (CAS NO.15829-53-5): 
ACGIH TLV-TWA 0.025 mg(Hg)/m3 (skin) DTLVS* The Threshold Limit Values (TLVs) and Biological Exposure Indices (BEIs) booklet issues by American Conference of Governmental Industrial Hygienists (ACGIH), Cincinnati, OH, 1996 Volume(issue)/page/year: TLV/BEI,1997 ACGIH TLV-Not classifiable as a human carcinogen DTLVS* The Threshold Limit Values (TLVs) and Biological Exposure Indices (BEIs) booklet issues by American Conference of Governmental Industrial Hygienists (ACGIH), Cincinnati, OH, 1996 Volume(issue)/page/year: TLV/BEI,1997

Mercury and its compounds are on the Community Right-To-Know List. Reported in EPA TSCA Inventory.

The safety information of Mercurous oxide (CAS NO.15829-53-5):
RIDADR:1641
HazardClass: 6.1(a)
PackingGroup: II
A poison. Flammable by chemical reaction; an oxidizer. Explosive reaction with hydrogen peroxide, chlorine + ethylene. Reacts violently with molten potassium, molten sodium, S, (H₂S + BaO + air). Forms explosive mixtures with nonmetals [e.g., phosphorus (impact-sensitive), sulfur (friction-sensitive)]. Incompatible with alkali metals, reducing materials. Dangerous; when heated to decomposition it emits highly toxic fumes of Hg. See also MERCURY COMPOUNDS, INORGANIC.

OSHA PEL: CL 0.1 mg(Hg)/m³ (skin)
ACGIH TLV: TWA 0.1 mg(Hg)/m³ (skin); BEI: 35 µg/g creatinine total inorganic mercury in urine preshift; 15 µg/g creatinine total inorganic mercury in blood at end of shift at end of workweek.
NIOSH REL: (Mercury, Aryl and Inorganic) CL 0.1 mg/m³ (skin)