SPIEGELEISEN

'Spiegeleisen' (German: ''Spiegel''— mirror or specular; ''Eisen''—iron) is a ferromanganese alloy containing approximately 15% manganese and small quantities of carbon and silicon. Historically, this was the standard form in which manganese was traded and used in steel making (see Bessemer process); today, manganese is usually traded and used in more concentrated form, 80% manganese content being typical.
Spiegeleisen is sometimes also referred to as ''specular pig iron'', ''Spiegel iron'', just ''Spiegel'', or ''Bisalloy''.