Pyrolusite naturally occurring

Manganese(Il) oxide is manufactured by the reduction of naturally occurring mangane.se(lV) oxide-containing ttres (e.g. pyrolusite) with carbon or methane ... 

The mineral pyrolusite, a naturally occurring manganese oxide, is brovm to black in colour. It is also possible that this may refer to an earth pigment with a high pyrolusite content, such as certain umbers. 

Manganese(IV) oxide is the only familiar example of this oxidation state. It occurs naturally as pyrolusite, but can be prepared in an anhydrous form by strong heating of manganese(II) nitrate ... 

Manganese(lV) oxide is the most important ore of manganese from which the metal is mostly manufactured. The oxide occurs in nature as the mineral pyrolusite as heavy gray lumps, or black when powdered. 

Several oxides of manganese occur naturally, the most important being pyrolusite (P-Mn02) South Africa holds... 

Of the mineral forms, only hematite appears to have been mined and used in its massive form these compounds otherwise occur as greater or lesser components in secondary pigments such as the ochres, umbers and siennas qq.v.), either in the natural state or from calcination. Akaganeite, lepidocrocite and maghemite (with pyrolusite) have been identified by Zolensky (1982) in prehistoric pictographs in Seminole Canyon, USA. 

MANGANESE DIOXIDE. MnO. Mol. wt. 87 sp. gr. 5. It is converted into MujOj at 535°C. Is insoluble in water and HNO3 and soluble in HCl. It occurs in nature as the blue-black mineral pyrolusite, which is mined in the former USSR, Gabon, Ghana, Morocco, South Africa, India, Brazil, Mexico, and in small quantities in several U.S. states, including Tennessee, Montana and New Mexico. 

In what physical slate does Pyrolusite occur in nature ... 

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