Pronunciation: [wˈɒlθəɹˌa͡ɪt] (IPA) 
The word "waltherite" is spelled with a silent "e" at the end, which is not pronounced. The IPA phonetic transcription for this word is /wɔːlθəraɪt/. The "w" is pronounced as in "wait" and the "a" sound is long like in "fall". The "th" sound is pronounced as in "truth" and the "er" sound is pronounced as in "her". Finally, the ending "-ite" is pronounced as "ait", just like in the word "ignite".
Waltherite is a term often used in the field of mineralogy to refer to a rare, secondary phosphate mineral. It is a hydrous calcium iron manganese phosphate with the chemical formula Ca[(Fe2+,Mn2+)8(PO4)6(OH)8·xH2O]. Waltherite usually forms as botryoidal or reniform crusts, with colors ranging from pale yellow to dark brown or nearly black. It has a vitreous to greasy luster and, when pure, it can display translucency. Because of its scarcity and limited distribution, waltherite is highly sought after by mineral collectors.
This mineral is named after Johann Jakob Walther, a German mineralogist. It is typically found in oxidized manganese ore deposits, usually associated with other phosphates such as phosphosiderite and vivianite. Waltherite can also occur in oxidized zones of iron-rich hydrothermal veins. It forms under low-temperature conditions and is commonly found in association with other secondary minerals like goethite and hematite.
From a structural point of view, waltherite belongs to the monoclinic crystal system. It typically crystallizes in prismatic or acicular crystal habits, although these are quite rare. The exact composition of waltherite can vary, with different cations such as magnesium, zinc, or aluminum substituting for iron and manganese in its crystal lattice. This variability in composition contributes to the wide range of colors observed in waltherite specimens.
