Stoneware --- First I need to tell you that the VAST majority of contact points you are going to find are going to be silver --- very rarely are you going to find points that are made of PGMs (platinum group metals) &/or for that matter points alloyed with PGMS - though there are of course exceptions - but it is VERY RARE
contact points that are made with PGMs &/or there alloys are only used in "
very specialized" applications such as
OLD telecom gear (before the world went digital) &/or as Lou pointed out aircraft motors (& other "
specialized" applications)
The oven thermostat, heating elements and those from electric water heaters have the largest contacts, washing machine and dryer timers from the older models are smaller but reasonabaly heavily plated
You will NEVER find PGMs in the points that come out everyday consumer appliances like this stuff --- they will ALL be silver points !!!
For what it is worth - in the something like 12 years I spent
making a living recovering & refining PMs the VAST majority of the silver I processed came from contact points
to put it in perspective I processed literally TONS of
whole contactors from magnetic disconnects, relays, & stuff like in your picture (from your landfill score)
out of those tons of "whole" contactors I recovered on an average (plus/minus) 2,000 ozt silver per year (or "about" 60 kilos/year)
Out of the many MANY tons of (whole) contactors I processed - only once did I run across points made with PGMs - those came from some OLD telecom gear
I posted about them here
https://goldrefiningforum.com/threads/three-types-of-contacts.23091/
Finding tungsten powder after leaching the appliance contacts, there is some tungsten powders left in the beaker.
What makes you so sure the powders in your beaker is tungsten --- it could be anything depending on "other" metals involved & or acids --- meaning different acids react differently with different metals & when it comes to contact points the metal(s) the points are attached to (bus bars) could be just about anything - so depending on the acid used to remove those metals you may dissolve some metal but not all metal leaving you with a sludge of who knows what - & you can not determine what these sludges are simply because of there color
Concerning tungsten/silver points - they are almost always found in hand thrown "circuit breakers" like the ones found in the electric panel in your house although you can also find them in large industrial size hand thrown circuit breakers
these type points generally run "about" 40% silver & 60% tungsten & they need to literally be
boiled in nitric acid for
hours in order to leach the silver out of the tungsten (sintered) matrix at which point yes you will get a tungsten sludge in the bottom of your beaker - meaning - unless you boil them in nitric - you will not leach enough silver out of them to get much if any tungsten sludge in the bottom of your beaker
Bottom line - although you may run across contact points that are made of PGMs &/or alloys of PGMs it will be very VERY rare & almost never (if ever) points that come out of normal everyday consumer products
Kurt